Creeping and crawling through children’s literature – A meeting of “two cultures”

Last weekend I was lucky enough to attend an unusual conference in Cambridge, “A Bug’s Life; Creeping and Crawling through Children’s Literature”.  It was unusual for me, as first it was at a weekend, second it was about insects in children’s books and third, all the other presenters and most of the delegates, were academics and PhD students from English departments.  I owed my presence at the conference as a result of my social media activities, in this case my Blog, as Zoe Jaques the organiser, had come across one of my diatribes about the lack of entomological accuracy in some insect themed books for children.  Zoe contacted me earlier this year and explained about her plans and wondered if I would be willing to contribute in my role as a professional entomologist with all expenses paid.  I didn’t take much persuading as I found the whole concept intriguing to say the least, and as an added bonus the guest author was the hugely successful Maya Leonard, author of Beetle Boy, Beetle Queen and the soon to be released, Battle of the Beetles.

I arrived at Cambridge Railway Station on the Friday night direct from France, having left Vinca at 8.45 am, to catch the train to Perpignan, then on to Paris on the TGV, then to London on the EuroStar, arriving in Cambridge courtesy of the local train, just after 9 pm.  A short taxi ride took me to Homerton College where Zoe had kindly arranged for me to stay in one of their excellent guest rooms.   After an excellent breakfast I made my way to the conference venue, following the very appropriate guide beetles 🙂

Our beetle guides

Once there I met the equally appropriately garbed Zoe and started to mingle with the delegates and other speakers, who among others, included Imogen Burt from BugLife

Zoe Jaques – the brains behind the conference, resplendent in beetle regalia.

 who opened the conference with a talk about the importance of insect conservation and the horrific and very inaccurate headlines perpetrated by the media to sell copy.  The conference programme was fantastic with a range of speakers from the Emeritus Professor, Peter Hunt, who invented the discipline of children’s literature in the UK to current PhD students such as Catherine Olver and Maggie Meimaridi with their delightfully punning talk titles, “Beeing oneself: individualism in twenty-first century fiction for teens” and “A ThousAnt plateaus”, respectively. There were a lot of puns buzzing and flying around at this conference, including a laugh-out loud presentation from Melanie Keene, “Bees and Parodies”.  We also had talks on insect scaling and cognition, fear of insects, The Very Hungry Caterpillar, racism and prejudice, and not strictly literature, a very entertaining talk by Zoe and her colleague David Whitley on the insects of Pixar animation.  My talk, not very imaginatively, was titled “The good, the bad and the plain just wrong”.  I focused mainly on the anatomy and taxonomic accuracy or not, displayed in children’s book, from the 1850s through to the modern-day.  This was a very personal selection, based on books that I had read as a child or read to my children, with a few examples from books I have come across in the last few years.  I mainly blamed the illustrators, although to be fair, some have done excellent jobs of portraying insects accurately and sympathetically.  I will be writing about this in a future post.

Maya Leonard completed the line-up with a totally Powerpoint-free extempore talk about her journey from entophobe to bestselling entophile; a ten-year journey.  A fantastic experience, if you ever get the chance to hear Maya speak, make sure you take the opportunity.

An experience not to be missed – Maya in full flow.

The “Two Cultures” in the title of this post refers to the idea of the novelist C P Snow, who at the time (1959) felt that science and humanities were two different antagonistic cultures, with science and scientists being looked down upon and scorned by those who inhabited the world of the humanities.  Put simply, Snow’s criticism was aimed at the fact that while those in the humanities felt that scientists were ignorant if they had not read Shakespeare, they did not perceive it as a failing if they were unable to state the Second Law of Thermodynamics.  This attitude may still persist in certain parts of the educated elite, in that it is seen as something to be proud of to say for example, that one is rubbish at maths, but that someone saying they have never read Jane Austen is seen as reprehensible.  This may no longer be the problem it was in 1959, although looking at the politicians wielding power in Westminster at the moment, the number of those with science degrees or an understanding of science, is lamentably low. There are indeed, as Maya pointed out in her talk, a lot of well-educated people, who know little or nothing about the natural world, entomology in particular.

Don’t get me wrong, this is not about how much better educated scientists are than those with degrees in the humanities, or those in the humanities giving short shrift to the ideas of scientists.  After all this conference was all about exploring the portrayal of an important part of the natural world; Insects and their allies, and seeking the viewpoint of a professional entomologist. Hardly the actions of Luddites unwilling to engage with new viewpoints.  I too was there to learn, as well as to inform.  In fact I was very apprehensive about my presentation.  As I pointed out in the introduction to my talk, although I have given talks to a diverse set of audiences, ranging from The Brownies to the Inner Wheel I had, until then, never given a talk to a room full of professional critics 🙂 I needn’t have worried, my talk was very well-received and generated lots of very perceptive and interesting questions.

I learnt a lot in the course of the day, not least the difference in how much can be read into the attitudes of the author and the subliminal messages that go unnoticed by the child reader, or as in my case, the adult reader, but are picked up and debated by those trained to absorb more from what they are reading than is actually on the printed page.  Although a great fan of Terry Pratchett’s Tiffany Aching series I had never taken on board the symbolism inherent in, for example,  A Hat Full of Sky’ until I heard Catherine Olver’s excellent talk on the symbolism of bees and hive minds in what I now know as YA (Young adult) fiction.  Similarly, until pointed out to me by Sarah Annes Brown during her talk on “Insects – a liberal litmus test?” the possibly racist and stereotypical portrayals of the characters in George Selden’s A Cricket in Times Square had completely escaped me.  I obviously spend too much time stressing out over the biological and anatomical aspects of the insect characters 🙂

The other thing that struck me very strongly was the difference in way in which language and PowerPoint was used by the speakers.  Biologists (and I think most scientists) are taught that the ideal slide should have no more than six bullet points and that under no circumstances should a slide be filled with a single block of text.  It this came as a surprise that we were asked on a number of occasions to spend a couple of minutes reading and digesting the contents of a slide filled from top to bottom with a quote from a book or paper.  I was also struck by the difference in the language used, “contextualise” and “narrative” being the two most common examples of words that are rarely uttered at an entomology conference.  That said, I confess that I used the word narrative several times in my own talk, but only one of my slides contained a quotation 🙂

The conference was an entertaining, educational, enjoyable and exhilarating experience and I am very grateful to Zoe for allowing me to take part in it.  I think the “Two Cultures” have a lot to learn from each other and Zoe is to be congratulated on having the idea and the perseverance to bring the project to fruition.  I very much look forward to future collaborations with her and others from the world of humanities.

And there were appropriate cakes 🙂

If you want to see the Tweets associated with the conference check out #bugznkidzlit



Filed under EntoNotes

“Ecological Armageddon”, we’ve known for years that insects are in decline so why so much fuss now?

Unless you have lived in a news vacuum for the last two weeks or so, you will be aware of the impending “Ecological Armageddon” that is about to be unleashed upon us.  A paper in the journal PLoS ONE  in which it was reported that there had been a 75% decline in the biomass of flying insects in protected areas in Germany since 1989 was the starting pistol that began the media frenzy.  The newspapers, both broadsheet and tabloids were quick to react as were the radio and TV stations and the coverage was global as this selection of links shows.

Entomologists were in great demand for a few days, all being asked to comment gravely on the paper and its implications.   I was also persuaded to air my thoughts on air, Talk Radio having caught me at an unguarded moment.  I should never have answered the ‘phone 😊

As the media frenzy subsided, the more considered responses began to appear.  Manu Saunders very sensibly attempted to put the study in perspective and point out its limitations. Two entomologists from the Game & Wildlife Conservancy Trust which hold an even longer data set, put forward their interpretation and an ecological consultancy also took the opportunity to comment.  The authors of the paper and the blog commentators were careful not to point the finger directly at pesticides as the main cause of this decline, although they did rule out climate change.  Agricultural intensification and the practices associated with it, were however, suggested as likely to be involved in some way, something that has been known for more than a century as the naturalist and novelist Gene Stratton-Porter  pointed out in 1909  in her novel A Girl of the Limberlost,

 Men all around were clearing available land.  The trees fell wherever corn would grow. The swamp was broken by several gravel roads…Wherever the trees fell the moisture dried, the creeks ceased to flow, the river ran low, and at times the bed was dry.  From coming in with two or three dozen rare moths a day, in three years time Elnora had grown to be delighted with finding two or three. Big pursy caterpillars could not be picked from their favourite bushes, where there were no bushes. Dragonflies could not hover over dry places and butterflies became scare in proportion to the flowers”.

What puzzles me about the media response is why now and why this particular study?  We have known for a long time that some insect groups have been in decline for many years.  The parlous state of UK butterflies and moths has been highlighted on more than one occasion over the last couple of decades (e.g. Conrad et al., 2004; Thomas et al., 2004; Fox et al., 2013), and declines in the abundance of bibionid flies (D’Arcy-Burt & Blackshaw, 1987), dragonflies (Clausnitzer et al., 2009) and carabid beetles (Brooks et al., 2012) have also been noticed and written about.  In addition, the results of a 42-year study on insects associated with cereal fields in SE England was published recently (Ewald et al., 2015), with little or no fanfare associated with it.  I commented on the decline of some insect species (and entomologists) in a blog post in 2013 and in December of last year, wrote about the general decline of insect numbers and lack of long term studies, incidentally citing the German study when it was originally published in a little known German publication back in 2013 and with far fewer authors 😊

The media response to this not new news puts me in mind of the Ash Die Back scare of 2012 when the press and politicians having

Pests and diseases recorded as entering the UK 1960-2015.  The two arrows indicate the replacement of local forest offices with central district offices and reduction in entomology and pathology staff.

been warned and made aware of the increasing incidence of non-native pests and pathogens entering the country for many years beforehand, suddenly, and in response to an intractable problem, went overboard in reporting doom and destruction

My hypothesis, for what it is worth, is that it is like when a tap washer starts to wear out, and your tap starts to drip. At first you just ignore it or turn the tap ever more tightly every time you use it.  Eventually something gives, either the tap breaks off (this happened to me very recently) or the drip becomes a flood.  Either way, something needs to be done, i.e. call the plumber.  In the case of the Ash Die Back episode, the UK government responded positively, albeit too late to prevent it, but by setting up the Tree Health and Plant Biosecurity Expert Taskforce of which I was privileged to be a member, recommendations were made that resulted in increased forest research funding and additional legislation being put in force to hopefully reduce the chances of further invasions.  I suspect that the current “Ecological Armageddon” scenario will not result in a similar response, although it may encourage research councils worldwide to think more seriously about funding more research into sustainable agriculture and for governments to encourage farmers to adopt farming strategies that encourage more wildlife and use fewer inputs.  At the same time, given the increasing number of studies that implicate urbanisation as a major factor in the decline of insect numbers (e.g. Jones & Leather, 2012; Dennis et al., 2017) it would behove local planning authorities to increase their efforts to provide much-needed green spaces in our towns and cities and to ban the use of decking in gardens and the replacement of front gardens with concrete and tarmac car parking areas.

What it does highlight as Manu Saunders said in her blog, is that we need funding for more long-term studies.  We also need to find instances where the data already exist but have not yet been analysed, amateur records and citizen science projects may be of use here.  Alternatively, as was very recently done in France (Alignier, 2018), it is possible, using the identical protocol, to resample a site after a gap of decades, to see what changes have occurred.

I hope for the sake of our descendants that the reports of an “Ecological Armageddon” have been exaggerated.  This should however, be a wake-up call to all those with the power to do something to mitigate the decline in biodiversity worldwide.  Governments need to respond quickly and to think long-term and responsibly.  The current attitude of politicians to adopt a short-term ‘how safe is my job’ political viewpoint is no longer a viable one for the planet. It is precisely that attitude that got us into the situation that we find ourselves in now.


Alignier, A. (2018) Two decades of change in a field margin vegetation metacommunity as a result of field margin structure and management practice changes. Agriculture, Ecosystems & Environment, 251, 1-10.

Brooks, D.R., Bater, J.E., Clark, S.J., Montoth, D.J., Andrews, C., Corbett, S.J., Beaumont, D.A., & Chapman, J.W. (2012) Large carabid beetle declines in a United Kingdom monitoring network increases evidence for a widespread loss of insect biodiversity. Journal of Applied Ecology, 49, 1009-1019.

Clausnitzer, V., Kalkman, V.J., Ram, M., Collen, B., Baillie, J.E.M., Bedjanic, M., Darwall, W.R.T., Dijkstra, K.D.B., Dow, R., Hawking, J., Karube, H., Malikova, E., Paulson, D., Schutte, K., Suhling, F., Villaneuva, R.J., von Ellenrieder, N. & Wilson, K. (2009)  Odonata enter the biodiversity crisis debate: the first global assessment of an insect group.  Biological Conservation, 142, 1864-1869.

Conrad, K.F., Woiwod, I.P., Parsons, M., Fox, R. & Warren, M.S. (2004) Long-term population trends in widespread British moths.  Journal of Insect Conservation, 8, 119-136.

Darcy-Burt, S. & Blackshaw, R.P. (1987) Effects of trap design on catches of grassland Bibionidae (Diptera: Nematocera).  Bulletin of Entomological Research, 77, 309-315.

Dennis, E.B., Morgan, B.J.T., Roy, D.B. & Brereton, T.M. (2017) Urban indicators for UK butterflies. Ecological Indicators, 76, 184-193.

Ewald, J., Wheatley, C.J., Aebsicher, N.J., Moreby, S.J., Duffield, S.J., Crick, H.Q.P., & Morecroft, M.B. (2015) Influences of extreme weather, climate and pesticide use on invertebrates in cereal fields over 42 years. Global Change Biology, 21, 3931-3950.

Fox, R. (2013) The decline of moths in Great Britain: a review of possible causes. Insect Conservation & Diversity, 6, 5-19.

Hallmann, C.A., Sorg, M., Jongejans, E., Siepel, H., Hofland, N., Schwan, H., Stenmans, W., Müller, A., Sumser, H., Hörren, T., Goulson, D. & de Kroon, H. (2017) More than 75% decline over 27 years in total flying insect biomass in protected areas. PLoS ONE. 12 (10):eo185809.

Jones, E.L. & Leather, S.R. (2012) Invertebrates in urban areas: a reviewEuropean Journal of Entomology, 109, 463-478.

Knowler, J.T., Flint, P.W.H., & Flint, S. (2016) Trichoptera (Caddisflies) caught by the Rothamsted Light Trap at Rowardennan, Loch Lomondside throughout 2009. The Glasgow Naturalist26, 35-42.

Thomas, J.A., Telfer, M.G., Roy, D.B., Preston, C.D., Greenwood, J.J.D., Asher, J., Fox, R., Clarke, R.T. & Lawton, J.H. (2004) Comparative losses of British butterflies, birds, and plants and the global extinction crisis.  Science, 303, 1879-1883.




Filed under Bugbears, EntoNotes, Uncategorized

Not all aphids get eaten – “bottom-up” wins this time

In the lecture that I introduce aphids to our entomology MSc students I show them two quotes that illustrate the prodigious reproductive potential of these fantastic animals.

“In a season the potential descendants of one female aphid contain more substance than 500 million stout men “– Thomas Henry Huxley (1858) and “In a year aphids could form a layer 149 km deep over the surface of the earth.  Thank God for limited resources and natural enemies” – Richard Harrington (1994).

I was a little discomfited whilst researching this article to find that both Huxley and I had been short-changed, although the original quote does hint at the mortality factors that an aphid clone faces during its life.

The original words and the morphed ‘quote’


Both these quotes acknowledge the contribution that both bottom-up and top-down factors have on aphid populations.  For those not familiar with the ecological jargon, ecologists have at times over the last 40 years or so, got quite territorial* about whether herbivorous insect populations are regulated by top-down e.g. predators or bottom-up e.g. host plant quality, factors (e.g. Hunter & Price, 1992).  Who is in charge of an aphid clone’s destiny, natural enemies or the food plant?

Aphids are the favourite food of several insect species; ladybirds (but not all species), lacewing larvae, hoverfly larvae, and also the larvae of some Cecidomyiid flies (Aphidoletes spp.), and Chamaemyiid flies (e.g. Leucopis glyphinivora).  They are also attacked by other Hemipteran species, such as Anthocoris nemorum.   Those insects that make a living almost solely from aphids, are termed aphidophagous and every three years you can, if you feel like it, attend an international conference devoted to the subject 🙂

As well as these specialist predators, aphids are also preyed upon by more generalist predators, such as carabid and staphylinid beetles, harvestmen and spiders. Aphids also provide a nutritious snack for birds and bats.  Faced with all these hungry and voracious predators you might wonder why it is that aphids ever get numerous enough to become pests.  There are two answers, their fantastic reproductive rates and second, aphids, despite appearing soft and squishy, do have anti-predator defence mechanisms.  These range from kicking predators in the face, dropping off the plant, gumming up the jaws of predators by smearing them with wax from their siphunculi, and even jumping out of the way of the predator (Dixon, 1958).  On top of all that,  many are extremely unpalatable and even poisonous.

Some population modelling work from the 1970s explains why aphids can often become pests, as well as introducing us to the concept of population dynamics geography; the endemic and epidemic ridges, and my favourite, the natural enemy ravine (Southwood & Comins, 1976).

The geography of population dynamics from Southwood & Comins (1976)


They suggested that if enough predators are already present in the habitat or arrive shortly after the aphids, then the aphid population either goes extinct or only reaches the “endemic ridge”.  The phenomenal rate at which aphids can reproduce under favourable conditions, usually gets them past the “natural enemy ravine” and up into “epidemic ridge” with only a slight slowdown in population growth.   Evidence for the “natural enemy ravine” is not very convincing and I feel that the suggestion that the dip in population growth at the start of the season is due to intermittent immigration by winged aphids and not the action of polyphagous predators (Carter & Dixon, 1981) is pretty convincing.   That said, later modelling work suggested that the subsequent growth of aphid populations could be slowed down by the action of natural enemies Carter et al., 1982).

Aphids, despite their ability to produce baby aphids extremely quickly, are not equally abundant all year round. Those of us who want to collect aphids know that the best time of year is early in the season, spring and early summer.  This is the time when the plant sap is flowing quickly and is rich in nutrients, especially nitrogen, which aphids need in large quantities.    A characteristic of aphid populations is the way they suddenly disappear during July, a phenomenon known as the “mid-summer or mid-season crash”.  This is not just a phenomenon confined to aphids living on ephemeral herbaceous hosts, it happens to tree-dwelling aphids too e.g. the sycamore aphid, Drepanoisphum platanoidis.  At Silwood Park, where I monitored sycamore aphid populations on fifty-two trees for twenty years**, I saw the same pattern of a rapid build-up followed by an equally rapid collapse every year.  The pattern was the same in both high population and low population years and happened at pretty much the same time every year.  Herbivorous insects are, as you might expect, strongly

High and low population years of sycamore aphid, Drepanosiphum platanoidis at Silwood Park

affected by the quality of their host plant, the availability of nitrogen in the leaves being of most importance (Awmack & Leather, 2002).  Aphids are no exception, and their whole-life cycle is adapted to the ever-changing, but predictable availability of soluble nitrogen and water in their host plants (Dixon, 1977).  Plants become less suitable for aphids as their tissues mature and they lock their nitrogen away in the leaves and other structures, rather than transporting it around in the phloem as they do in spring and autumn (Dixon, 1976).

Aphids respond in two ways to a decline in the nutritional quality of their host plant, they reduce the number of offspring they produce (e.g. Watt, 1979) and those offspring they produce are winged (e.g. Parry, 1977), or if already winged, more likely to take flight and seek new better quality host plants (e.g. Dixon, 1969; Jarosik & Dixon, 1999).  In some aphids there is also an increase in intrinsic mortality (e.g. Kift et al., 1998).

The mid-season crash is not confined to abundant and common aphids, rare aphids show exactly the same changes in their populations, and this is similarly attributed to changes in the nutritional quality of the aphid host plant leading to increased dispersal (e.g. Kean, 2002).

Population crash of the rare aphid Paradoxaphis plagianthi in New Zealand (data from Kean, 2002).

Although some authors, notably Alison Karley and colleagues have suggested that it is the action of natural enemies and not host nutrition that drives the mid-season crash (Karley et al., 2003, 2004), the overwhelming evidence points to the production of winged (alate) morphs and their dispersal, being the major factor in causing the mid-season crash as the graphs below illustrate.

Cereal aphids on wheat showing increased alate production coinciding and subsequent population crash on cereal crops. Data from Wratten, 1975).

Green spruce aphid, Elatobium abietinum on Norway spruce at Silwood Park, showing the population crash and associated increase in the number of winged aphids. Data from Leather & Owuor (1996).

Green spruce aphid in Ireland, population crash associated with marked decline in fecundity and production of winged forms. Data from Day (1984)

Data presented by Way & Banks (1968) might lend some support to the idea that natural enemies cause the mid-season crash.  A close examination of the data however, which might at first glance suggest that keeping natural enemies away, allows aphid populations to prosper, reveals that the process of excluding natural enemies also prevents the dispersal of the winged aphids, which have no choice but to stay on the host plant and reproduce there.

Aphis fabae populations on Spindle bushes from Way & Banks (1968). Top line shows the population kept free of predators until August 2nd, bottom line, exposed to predators.

Moreover, as the authors themselves state “the rise to peak density in each year, coincided with an enormous increase in the proportion of individuals destined to become alatae” (Way & Banks, 1968).   I do not dispute that natural enemies have an effect on aphid populations, but in my opinion, the evidence does not support the hypothesis that they are the driving force behind the mid-season crash.  Rather, the major factor is the reduction in host quality, caused by a decline in the nutritional status of the plant and overcrowding of the aphids, leading to reduced fecundity and an increase in winged dispersers.

I don’t deny that the natural enemies do a very good mopping-up job of those aphids that are left behind, but they are not the force majeure by any stretch of the imagination. Most aphids do not get eaten 🙂



Awmack, C.S. & Leather, S.R. (2002) Host plant quality and fecundity in herbivorous insects. Annual Review of Entomology, 47, 817-844.

Carter, N. & Dixon, A.F.G. (1981) The natural enemy ravine in cereal aphid population dynamics: a consequence of predator activity or aphid biology? Journal of Animal Ecology, 50, 605-611.

Carter, N., Gardner, S.M., Fraser, A.M., & Adams, T.H.L. (1982) The role of natural enemies in cereal aphid population dynamics. Annals of Applied Biology, 101, 190-195.

Day, K.R. (1984) The growth and decline of a population of the spruce aphid Elatobium abietinum during a three  study, and the changing pattern of fecundity, recruitment and alary polymorphism in a Northern Ireland Forest. Oecologia, 64, 118-124.

Dixon, A.F.G. (1958) The escape responses shown by certain aphids to the presence of the coccinellid Adalia decempunctata (L.). Transactions of the Royal Entomological Society London, 110, 319-334.

Dixon, A.F.G. (1969) Population dynamics of the sycamore aphid Drepanosiphum platanoides (Schr) (Hemiptera: Aphididae); migratory and trivial flight activity. Journal of Animal Ecology, 38, 585-606.

Dixon, A.F.G. (1976) Factors determining the distribution of sycamore aphids on sycamore leaves during summer. Ecological Entomology, 1, 275-278.

Dixon, A.F.G. (1977) Aphid Ecology: Life cycles, polymorphism, and population regulation. Annual Review of Ecology & Systematics, 8, 329-353.

Harrington, R. (1994) Aphid layer. Antenna, 18, 50-51.

Hunter, M.D. & Price, P.W. (1992) Playing chutes and ladders – heterogeneity and the relative roles of bottom-up and top-down forces in natural communities. Ecology, 73, 724-732.

Huxley, T.H. (1858) On the agmaic reproduction and morphology of Aphis – Part I. Transactions of the Linnean Society London, 22, 193-219.

Jarosik, V. & Dixon, A.F.G. (1999) Population dynamics of a tree-dwelling aphid: regulation and density-independent processes. Journal of Animal Ecology, 68, 726-732.

Karley, A.J., Parker, W.E., Pitchford, J.W., & Douglas, A.E. (2004) The mid-season crash in aphid populations: why and how does it occur? Ecological Entomology, 29, 383-388.

Karley, A.J., Pitchford, J.W., Douglas, A.E., Parker, W.E., & Howard, J.J. (2003) The causes and processes of the mid-summer population crash of the potato aphids Macrosiphum euphorbiae and Myzus persicae (Hemiptera: Aphididae). Bulletin of Entomological Research, 93, 425-437.

Kean, J.M. (2002) Population patterns of Paradoxaphis plagianthi, a rare New Zealand aphid. New Zealand Journal of Ecology, 26, 171-176.

Kift, N.B., Dewar, A.M. & Dixon, A.F.G. (1998) Onset of a decline in the quality of sugar beet as a host for the aphid Myzus persicaeEntomologia experimentalis et applicata, 88, 155-161.

Leather, S.R. & Owuor, A. (1996) The influence of natural enemies and migration on spring populations of the green spruce aphid, Elatobium abietinum Walker (Hom., Aphididae). Journal of Applied Entomology, 120, 529-536.

Parry, W.H. (1977) The effects of nutrition and density on the production of alate Elatobium abietinum on Sitka spruce. Oecologia, 30, 637-675.

Southwood, T.R.E. & Comins, H.N. (1976) A synoptic population model.  Journal of Animal Ecology, 45, 949-965.

Watt, A.D. (1979) The effect of cereal growth stages on the reproductive activity of Sitobion avenae and Metopolphium dirhodum. Annals of Applied Biology, 91, 147-157.

Way, M.J. & Banks, C.J. (1968) Population studies on the active stages of the black bean aphid, Aphis fabae Scop., on its winter host Euonymus europaeus L. Annals of Applied Biology, 62, 177-197.

Wratten, S.D. (1975) The nature of the effects of the aphids Sitobion avenae and Metopolophium dirhodum on the growth of wheat. Annals of Applied Biology, 79, 27-34.


Post script

For those interested this is how Huxley arrived at his number of potential descendants, and here I quote from his paper,  “In his Lectures, Prof. Owen adopts the calculations taken from Morren (as acknowledged by him) from Tougard that a single impregnated ovum  of Aphis may give rise, without fecundation, to a quintillion of Aphides.” I have not, so far, been able to track down Tougard.

Morren, C.F.A. (1836) sur le Puceron du Pecher, Annales des Sciences Naturelle series 2. vi.

You may not know what a grain is, so to help you visualise it, 7000 grains equals a pound so 2 000 000 grains gives you 286 pounds, or 20 stone or approximately 130 Kg depending on where you come from J


*and generated some magnificent paper titles and quite acrimonious responses J Hassell, M.P., Crawley, M.J., Godfray, H.C.J., & Lawton, J.H. (1998) Top-down versus bottom-up and the Ruritanian bean bug. Proceedings of the National Academy of Sciences USA, 95, 10661-10664.

**A true labour of love as I also counted maple aphids, orange ladybirds, winter moth larvae and any of their predators and parasites that I came across J



Filed under Aphidology, Aphids

Pick and mix 12 – Ten largely entomological and tree-related links

All sorts


Plants for bugs – making gardens insect friendly

Bugs for humans – making insects more attractive as food

Bugs for bugs – making carrion diets better for their offspring

Bugs for tourism – fireflies keeping a Mexican town alive

Dead trees for bugs – a free issue on saproxylic insect conservation

How trees can help cool cities and a link to the full report

Courtship behaviour of the Grayling butterfly via Ray Cannon

The chemistry of autumn colours – with a nice downloadable graphic

Why natural history teaching needs to be an increasing part of university education

Good news for those of us who like butter, cheese and meat 🙂

Autumn is on the way

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Filed under Pick and mix

Bringing ecology blogging into the scientific fold: measuring reach and impact of science community blogs

At the end of the year there is a tendency for some scientific bloggers to take advantage of the statistics provided by their host platform to produce a round-up of their year and to compare their figures with previous years.  I too am one of the number crunchers and revel in the data available 🙂  One of the frustrating things, for me at any rate, is the lack of a benchmark, how are you doing compared with other bloggers?  This year I decided to try and get some data and approached Jeff Ollerton to see if he would let me look at his 2016 data, which he kindly did and this allowed me to produce a comparative graph.  Much wants more.  As an entomologist an n of 2 is small beer.  I needed more data to satisfy my craving.  I also talk to our postgraduate students about the value of social media, including blogging, but rely mainly on personal anecdotes.  What was needed was something concrete to support my assertions.

I subscribe to, and follow a number of blogs, but there are a few that I feel are somewhat similar in their aims and scope to mine.  One is Jeff Ollerton’s Biodiversity Blog, the others are Dynamic Ecology, Ecology Bits, Ecology is Not a Dirty Word, Scientist Sees Squirrel and Small Pond Science.  Jeff is also a follower of these blogs and when I suggested that it would be a good idea to try to write something about the value of blogging to academics and why our employees should support us in our endeavours he promptly suggested that we get in touch with those bloggers.  I couldn’t see a downside to this so first approached Manu Saunders of Ecology is Not a Dirty Word and Steve Heard of Scientist Sees Squirrel as these were the two bloggers with whom I had interacted most.  Steve then helped bring the others on board and that is how it all began (at least that is how I remember it).

The Blogging Consortium

Manu very kindly took charge of the data collation and I made a first stab at drafting the paper in mid-January.  Steve did a very good job of rewriting it and Meg Duffy (Dynamic Ecology) Jeff Ollerton and Amy Parachnowitsch (Small Pond Science) got into the swing of things as well.  By the end of January we were really motoring and bouncing ideas of each other and the rapidly growing draft.  As with all non-mainstream activities, the day jobs got in the way and we had a couple of months where very little happened.  I felt that things were slipping a little and in the spring had another go at the draft and this stimulated another flurry of action from what we were now calling the blogging consortium, with major contributions from Meg, Jeff and Steve, which put us all on our mettle and something that was beginning to look like a completed paper appearing.  By May Manu had got us all working on a Google Doc document which greatly improved our efficiency.  As we were now heading toward June, some further analysis was needed and Manu bravely volunteered to become the lead author and general butt kicker 🙂 It worked, and by the beginning of July we were ready to submit and had started discussing potential journals.  As the paper was all about science communication we were very keen to get it in a high-profile Open Access journal, but one that didn’t charge an arm and a leg as our paper had no grant income associated with it.  After a couple of enquiries Manu found a journal that fitted our requirements and was willing to have a look at it and on July 20th 2017 Manu submitted our paper to Royal Society Open Science.  Six weeks later we were euphoric!

Oh frabjous day!

The comments of the reviewers were some of the best I have ever seen, and I submitted my first paper in 1979 🙂  I have never had the word limpid applied to my writing, it just shows what can be achieved by cooperation.   I can’t resist sharing some of the comments from the reviewers

Associate Editor Comments to Author:


Both reviewers are very positive about this manuscript and indeed I agree with them. It is an important piece and a very inspirational read.

Reviewer: 1

At one time, my favourite t-shirt slogan was “More people are reading this t–shirt than your blog” – those days are clearly gone as this paper shows, at least in ecology! ……..Their thoughts on citing blogs will, I suspect, launch many posts and comments on their respective blogs. I think this paper will be an important contribution to what is very much a developing field. I have no comments to add and, for the first time for me, I recommend acceptance without revision.

Reviewer: 2

 This is a fantastic and much needed piece that deserves to be published widely. ……….The authors clearly state this upfront: ‘academics wish to understand whether particular activities influence various audiences’. I command the authors for this rare instance of honesty and for aiming to publish this manuscript with the best academic journals in their discipline. The manuscript is limpid and very well written. The style is engaging and the results significant for the wider academic community. I fully support its publication.


These last nine months working on the paper were personally very rewarding and to me, a vindication that becoming a blogger was a good decision.  It was also a huge buzz to work with such a dynamic group of bloggers.  I think Steve sums it up for all of us in this Tweet

If you are not yet a science community blogger or don’t think that they have a place in mainstream science, please take the time to read our paper which you can find here.  It won’t cost you anything but time 🙂 and if any reporters are reading this – here courtesy of Manu, is our press release.

Blogs are no longer simply online personal journals. We define an overlooked category of blogs that holds immense value for the scientific community: science community blogs are written by practising scientists for scientists. As academics and active bloggers, we use data from our own blogs to show how science community blogs are a valuable outreach and professional development tool. Blogs are also a citable primary source with potential to contribute to scientific knowledge. It’s time for blogs to be accepted as a standalone medium with huge benefits for individual scientists and the science community as a whole.   


Post script

If you want to know what my fellow authors thought about our collaboration you can find Manu’s story here, Steve’s here, Amy and Terry’s here and Meghan’s here.


Filed under Science writing

The bane of PhD students– the General Discussion

This year has been a bit of a bumper PhD submission year for me, five of my PhD students have come to the end of their time, and have submitted, or will soon be submitting their theses.  In my experience, 48 successful students and counting, it is relatively easy to reassure PhD students that their worries about the structure of their thesis, the appropriateness of their analysis and how many tables and figures they should have, are not justified. Many of them already have papers in print or in press by the writing-up stage so they only need a little bit of reassurance about the quality of their work.  The bit that seems to worry them most is the General Discussion.  My advice to them was, and is, the same as that given to me by my supervisor 37 years ago, “spread your wings, sell your work, don’t be afraid to speculate a little, enjoy yourself and make sure you don’t just summarise your thesis”. 

This uncertainty about how to handle the General Discussion is not just a foible of my students.  My impression over the last few years, borne out by the increasing frequency on which I comment on the shortcomings of the General Discussion of the PhD theses that I examine (now more than sixty) is that General Discussions are not what they used to be.  I too often find myself reading a series of lightly edited chapter abstracts, which in my opinion is not a General Discussion. Am I, however, suffering from grumpy old git syndrome or were General Discussions more general in the days of my youth?  How for example, does my General Discussion stack up compared with that of the modern-day PhD student? Did I practice what I now preach?

I do of course still have a copy of my thesis (Leather, 1980), two to be precise. Both my parents were biologists, albeit botanists, so I felt obliged to give them a copy, which I retrieved when clearing my Mother’s house after her death.  The upshot being that I have no excuse for not being able to find a copy from which to do a critical appraisal of my General Discussion. My thesis was written before Word Processors existed, and when computers occupied their own buildings. It was typewritten (by me using a Silver Reed A3 typewriter) and so no electronic copies are available.  As a consequence, I have had to scan the parts relevant to my story; hence the poor quality of the illustrations 🙂

At this point, I should point out that although I was trained as an agricultural entomologist and my PhD was about an agricultural pest, the bird cherry-oat aphid, my supervisor, Tony Dixon, was and still is, an ecologist.  Our lab was thus a mixture of pure and applied ecologists, some of whom weren’t even entomologists 🙂 This meant that I was exposed to a wider range of ideas than if I had just been in a lab of only applied entomologists.  Despite not being overly mathematical or theoretically inclined, I’m pretty much an empirical ecologist (field and lab), I was very impressed by the late, great E.C. Pielou, to the extent that I bought her book Ecological Diversity and read it cover to cover*.  Working with a host alternating aphid, I immediately latched on to her definition of seasonality as being synonymous with environmental variability (Pielou, 1975) and decided to coin a new term, seasonability** .

An excellent start, the title page doesn’t even mention the words General Discussion 🙂


I defined seasonability as being “the pre-programmed response to predictable environmental change” in  my terms this meant that the organism, in this case my aphid, anticipates the trend in conditions, something I, and a more mathematically inclined colleague did actually show a couple of years later (Ward et al., 1984).  I then drew the analogy that an aphid clone could be equated with Harper’s visualisation of a plant being constructed of a series of genetically identical modular units (Harper, 1977), i.e. each individual within the clone, although being genetically identical has a specific (and seasonal) function I also managed to slip in a reference to my other ecological hero, Dan Janzen at this point (Janzen, 1977) 🙂

I see that I was keen to introduce new terms, as my second figure shows.  I was amused to see in figure legend that I describe the x-axis as food quality but label it as host quality in the

A pretty lousy figure, but remember we had to draw our figures by hand in those days. Here I attempt to coin another new usage, this time refluence, to indicate the flowing back of the clone to the primary host.

figure, doing something that in later years I have waxed wrathfully against (Leather & Awmack, 1998; Awmack & Leather, 2002).  In this case, food (nutritional) quality is the term I should have used although I could argue that the build-up of natural enemies on the secondary grassy hosts and the predictable absence of natural enemies on the primary host, could justify the use of the term host quality, but that would be post hoc sophistry and best avoided 🙂

I was obviously also very keen to introduce new meanings to words as my third figure shows.

Yet another attempt to coin a new meaning for an existing word


At no point however, did I summarise what was in each chapter.  I referred in passing to one…”It is now fairly certain from the evidence presented on the effects of growth stage (Chapter 4) that..” and the four figures are unique to my General Discussion, even the two that contained data points, so I can pat myself on the back in that respect.  Although I did not extend my discussion to other taxa, I did range far and wide across the aphid world so I think that fulfilled the brief of spreading my wings, and boy did I try and sell my work.

I also notice that the 25-year-old me tried very hard to use a different sort of language in his General Discussion such as, “lends further credence to the concept of seasonability” which is followed in the next sentence by “..when the bursting of the buds of the tree host or resurgence of sap in the perennial herbaceous host, herald the start of egg hatch”. Yes, I actually used the word herald, but then, this is the guy who prefaced his thesis with these two quotes.

The Steinbeck quote (Doc from Sweet Thursday, does still sums up pretty much what I want to do with my life.


So what does the 62-year-old Professor of Entomology think about the efforts of his younger self?  I may be slightly biased, but I think it is a reasonable effort and as an examiner I wouldn’t have any major problems with it although I suspect that I would be tempted to have a gentle dig at the attempts to coin new terms. Overall I would rate it as B+.

In case you wondered , although I never published, or even tried to publish my General Discussion, all the ideas, except for the terms which were petty awful, (or naff as we would say in the UK), have made it into print at some time.

To reiterate, my advice to PhD students struggling with your General Discussion is “spread your wings, be bold, sell your work, don’t be afraid to speculate a little, enjoy yourself and most importantly,  definitely make sure you don’t just summarise your thesis”


Awmack, C.S. & Leather, S.R. (2002) Host plant quality and fecundity in herbivorous insects. Annual Review of Entomology, 47, 817-844.

Leather, S.R. (1980)  Aspects of the Ecology of the Ecology of the Bird Cherry-Oat Aphid, Rhopalosiphum padi (L.).  Unpublished PhD Thesis, University of East Anglia, Norwich.

Leather, S.R. & Awmack, C.S. (1998). The effects of qualitative changes of individuals in the population dynamics of insects. In Insect Populations In Theory and in Practice (ed. by J.P. Dempster & I.F.G. McLean), pp. 187-206. Kluwer, Dordrecht.

Harper, J.L. (1977) Plant Population Biology, Academic Press, London.

Janzen, D. H. (1977) What are dandelions and aphids? American Naturalist, 111, 586-589.

Pielou, E.C. (1975) Ecological Diversity, John Wiley & Sons Inc., New York.

Ward, S.A., Leather, S.R., & Dixon, A.F.G. (1984) Temperature prediction and the timing of sex in aphids. Oecologia, 62, 230-233.


*I also bought her book Mathematical Ecology but didn’t manage to read it cover to cover 🙂

**I had great hopes of getting my General Discussion published and my new term being adopted by ecologists around the world 🙂


Filed under Science writing, Teaching matters

Challenges and rewards – Why I started, and continue blogging

If you are reading this article this afternoon (13th September 2017) it is quite possible that I am at this very moment giving my talk about the challenges and rewards of blogging to a live audience at ENTO’17 in Newcastle J  In my talk, I began by explaining how it was that I became a fan of social media, first Twitter and then as a blogger.  I have already written about my conversion in an earlier post and how much I feel that social media adds to academic life, so I will not bore you with the whole story again.

  Suffice it to say pre-Twitter and pre-blogging I was writing a lot, but mainly to the wrong audience.

The second part of my talk attempted to answer the following questions. As an academic why should you blog?  What are the benefits?  What are the risks?  What are the challenges? Is it part of your day job?  More importantly, how can you convince your university or research institute that you should spend office time blogging?  What follows is the ‘script’ of my talk.

I started blogging because I felt that the way I was trying to get the importance and wonder of entomology across to non-entomologists was too limited.  I was not interacting with enough people outside the field, I needed to widen the scope of my activities.  Yes I was going into schools and talking to natural history societies, gardening clubs and on occasions youth groups and organisations like the Women’s Institute or the U3A, but I was only talking to tens of people. I wanted (needed) to talk to hundreds, even thousands of people to feel that I had a chance of getting my message across that the future of the natural world lay in an understanding of the invertebrate world and not of the “large charismatic mega-fauna”.  Hence my leap into the world of Twitter, and certainly with a following of over 5000, I am now potentially talking to thousands of people, according to my analytics my Tweets earn nearly 5 000 impressions a day.   The trouble with Tweets is that by their very nature they are transient and flow down the Twitter timeline to obscurity at a tremendous rate.  They are also not easily reference-able.  A blog on the other hand, if hosted on a reputable site, is as permanent as anything is these days, and as each post has a unique address, also has the advantage of being able to be linked to and found by search engines.  It was thus a logical step to launch a blog which is what I did, and Don’t Forget the Roundabouts was born.

A blog is born

I did not take this step lightly.  As the point of starting a blog was to make an impact, it could not be anonymous.  The content of the blog needed the backing of my professional reputation to hopefully give it the stamp of reliability and authority.  I was, and still am, putting my reputation on the line every time I post a blog article. It was thus with some sense of trepidation that I went public.  Writing a blog is a whole different thing to submitting a paper to a journal where you are subjected to peer review and your readership is pretty much limited to people who are very similar to yourself and whom have access to scientific journals.  Anyone with access to the internet can find, read and comment on a blog. A scary thought.  I felt it was worth it and still do. There were two other reasons besides my wish to increase the range of my outreach and to increase the level of interactions, that made the idea of starting a blog seem logical.

Reasons to start a blog

As a teenager I loved English, both language and literature (I still do, I have a personal library of over 10 000 books) and even had aspirations of becoming a novelist.  As those of us who have been around for a longish time will know, as you become more successful at getting grants and increasing the size of your research group, you get further and further away from the bench and/or field and do more and more ‘editing’ and commenting on other people’s writing.  In my case this had resulted in me finding it more and more daunting when faced with a blank sheet of paper or an empty word processing document. I saw the prospect of producing blog articles as a way of getting back into the habit of starting from scratch and also of learning a more relaxed and accessible style ready for my retirement plans of writing “popular”* entomology books. Finally, I thought it might be fun, my late father often voiced the opinion (especially when I was a teenager) that I “loved the sound of my own voice”.  Writing a blog does indeed give me the opportunity to sound off now and then and I make all sorts of fantastic discoveries when I am doing the background research for an article.  I freely confess, I enjoy writing my blog immensely.  It really is great fun.

Is it all positive?  Of course there are challenges, it would be foolish to deny it.  Finding the time to manage a blog can be a problem.  I am not retired, I have a full-time academic position, running a research group, editing journals, reviewing papers and grant proposals, writing and co-writing scientific papers, sitting on committees, and of course teaching students, both undergraduates and postgraduates.   Writing a blog is yet another call on my time, but one I am happy to heed.   I do blog writing and research at work

Enough to put you off?

and at home.  My contract does actually have a paragraph that mentions outreach so I feel justified in doing this.  Another challenge that might seem daunting is that of coming up with topics to write about.  Before I went public, I wrote five articles and filled an A4 piece of paper with potential topics that I thought would be fun to write about and of interest to others.  In reality I found that just living life provides topics enough to allow me to produce an article every couple of weeks.  There is always something that sparks an idea for a potential blog article, be it a scientific paper I read, something in the news or even as has happened twice now, a piece of fiction.

A challenge to some bloggers is that of motivation.   Unless you happen to be paid to be a blogger or make a living from it, then it can be hard to make the time and take the effort to write something regularly.  Luckily for me, I am somewhat competitive, even when the only other entrant in the race is myself.  I set a target of two articles a month but regularly find myself doing three, just to make sure that I am ahead of schedule and also I get quite a buzz on ‘publication’ day when the daily view total shows a spike in response to your activity 🙂

The publication day spike

 I have to admit that the fact that WordPress generates a number of statistics that you can track and compare, gives me plenty of motivation 🙂

The other challenge which I alluded to is the slightly anxious feeling that you get every time you publish an article.  Firstly as I mentioned earlier, because I am blogging as me, I really, really want what I say to be correct.  I find that I do as much, if not more background reading for a blog article as I do for a scientific paper.  I definitely do a lot more historical reading for the blog articles because it is very interesting and I also find it fun to delve back to the origins of a topic.  If I had not written an article about aphid symbionts I would never have discovered that Thomas Henry Huxley had worked on aphids which made me even impressed with him than before. The other times that I feel anxious are when I publish something that Is not strictly within my field but moe of an opinion piece.  When I got upset about he British Ecological Society (BES) and their conference catering policy I wrote rather an angry, although, at least in my opinion, a well-argued article.  I was somewhat hesitant in pressing the publish button, but went ahead and did so, and then sat back waiting for the angry responses from vegetarians and vegans.  To my surprise the expected lambasting did not materialise and I received several complimentary comments and emails.

Having a go at the British Ecological Society

The BES were even kind enough to publish a slightly edited version in their Bulletin.  In some ways I have been slightly disappointed that this, and other articles dealing with ‘controversial’ viewpoints have not generated more critical responses, although I guess I should count my blessings and not angle for brickbats.

Enough about the challenges, what about the benefits?  Have I made an impact?  As far as I am concerned the answer is a resounding YES.  I am read all around the world and I am pretty certain that my 175 blog posts have been read more than my 230 scientific papers.

A worldwide reach – I have been read by someone in almost every country in the world

I am particularly proud of having one of my blog posts referenced in a book about preparing for PhD vivas (Smith, 2013).

This post made an impact –

I have also been invited by magazines and societies to convert some of my blog posts into articles for publications aimed at reaching more general audiences in an accessible and informative way.

Making an impact and bringing entomology to a wider audience

More conventionally, some of my blog posts have gone mainstream and appeared in scientific journals, a bit of reverse outreach 😊

Some of my blog posts that have made it into the scientific literature

Something that may put people off blogging is the possibility that their employer may not see a benefit in their activity and only not encourage but perhaps even discourage, their staff from becoming bloggers.   It was to counter this perception that a group of like-minded bloggers and I got together to present an analysis of the value and impact of blogging in ecology.  It was an interesting and rewarding exercise** and last week we were rewarded by having our paper accepted for publication in a prestigious journal.

Squaring the circle – a mainstream paper about the benefits of blogging for scientists

Proof that this was a fun project to collaborate on and write about

I think that there is a very strong case for more scientists to become bloggers, but if you do decide to take up the challenge and become a blogger you should first ask yourself exactly what it is you hope to get from it.  Is it just for pleasure, is it for outreach, to practice writing or to draw attention to yourself to increase interactions with others in your disciplines?

Three simple rules to ease you into the blogosphere

Whatever your reasons there are things that you can do to make your blog a success and help you overcome the challenges I have outlined above.  First, be well prepared have some articles in reserve, especially when you launch your blog. It is also a good idea to post at regular intervals, not necessarily often.  Having a ‘deadline’ will help you with your writing and time management and people will start to expect to hear from and may even become subscribers to your blog.  It is also important not to get downhearted or impatient.  It takes time to build an audience.  Blogs grow at different rates depending on a number of factors including blogging frequency and audience interaction (Saunders et al., 2017).

A frequent poster

My blog, regular but not as frequent as Jeff Ollerton’s Biodiversity Blog

Finally, it is important to do as much as possible to publicise your blog, use the tag function to help search engines direct people to your blog and I would urge you to join Twitter and do remember to use all the publicise buttons that your blog host provides.

I look forward to seeing a plethora of new entomology and ecology blogs. Happy Blogging.



Saunders, M.E., Duffy, M.A., Heard, S.B., Kosmala, M., Leather, S.R., McGlynn, T.P., Ollerton, J. & Parachnowitsch, A.L. (2017) Bringing ecology blogging into the scientific fold: measuring the reach and impact of science community blogs. Royal Society Open Science,

Smith, P.H. (2013) The PhD Viva, MacMillan Education, UK.

*assuming anyone wants to read them of course 🙂

**there will of course be a blog about this in the near future.


Filed under Science writing

Entomological classics – the sweep net

I am certain that everyone who has studied biology at university and/or been on a field course, will have used a sweep net and heard the phrase “It’s all in the wrist”.  Along with the pitfall trap it is the most commonly used entomological sampling technique used today.  Although the premise is simple enough, a sturdy net, attached to a handle that is swept along, through or above low-lying vegetation, when used as a scientific tool and not just as a collecting device, things become somewhat more complex.  The sweep net, as an insect collecting device, has been around for at least 180 years, the earliest reference that I have been able to find being Newman* (1835).  There are a number of slightly later references in both general entomology texts and group specific books (e.g. Newman, 1844; Clark, 1860; Douglas, 1860; Douglas & Scott, 1865). Instructions for their use at this time are minimal, as this extract from Newman (1841) illustrates.

Newman (1841) a very brief description indeed.

This slightly later description of how to make a sweep net is, however, much more detailed, albeit somewhat sexist.

From Stainton (1852), although he seems to be quoting Newman.  Apparently Victorian men were unable to sew.

More detailed, albeit fairly basic instructions on how to use a sweep net can be found in those two invaluable sources, Ecological Methods (Southwood & Henderson 2004) (two pages) and Practical Field Ecology (Wheatear et al., 2011) (one page).  I was amused to see that the text in Southwood & Henderson was identical to that of the first edition (Southwood, 1966).

Now we come to the wrist action. There are a surprising number of ways in which you can swing a sweep net, but they all depend on the wrist moving your hand, and hence the net, in a figure of eight. The two most commonly used are what I think of as the one row side step, and the double front step.  In the former you walk in a straight line swinging the net backwards and forwards at your side, ideal for sampling a row crop. The latter, the double front step, is similar, but instead of swinging the net at your side, you swing it side to side in front of you as you walk along.  In a crop, this is great for sampling multiple rows, in a non-crop a good way of covering a nice wide area of vegetation. There are a further two techniques specifically designed for sweeping the upper part of vegetation, both originally devised for sampling soybean insects, the lazy-8 and the pendulum (Kogan & Pitre, 1980).  Both these involve having the net raised, the lazy-8 with the net raised above the crop at the back and front swings, whereas in the pendulum, the net is kept within the crop on the fore and reverse swings.  The final bit of wrist action, and arguably the most important and difficult to learn, is the flick-lock, which neatly seals the net and stops your catch escaping.

Having completed your sample of however many sweeps (remember a complete sweep is the figure of eight), and sealed your net, the next step is to transfer your catch to your collecting tubes, bags or jars.  A good sweep net, as well as being made from tough material, should be a bit sock shaped.  By this I mean that there is a ‘tail’ at the base of the net which helps make your catch more manageable if you are transferring directly to a plastic bag, as you are able to grab the net above the ‘tail’ end and push it into the collecting bag, before everting the net.

Two examples of sweep nets, a large and a small one.  You can also get a medium one in this series supplied by the NHBS web site for about £34.

When I was a student, the sweep nets we were supplied with, were large enough to stick not just your head inside, but also to get your arms in, so that you could Poot up anything interesting, your shoulders forming the seal to the net.  Admittedly you did sometimes have an angry bee or wasp to contend with, but that was a rare event 🙂  Nowadays, sweep nets seem to be constructed on a much more modest scale, which makes sticking your head, let alone your shoulders into one, somewhat difficult.

Even the biggest modern one is too small for me to get my arms in to do some Pooting.

I was pleasantly surprised on an ERASMUS exchange visit to the University of Angers a few years ago, to find that the French, or at least those in Angers, were using sweep nets that were big enough for me to actually delve inside just as I did when I was a student 🙂

The joys of a sweep net with a view 🙂

Despite their undoubted popularity, value for money and relative ease of operation, there are a number of problems associated with sweep netting as a sampling technique.  Although these problems are summarised elsewhere (Southwood & Henderson 2004; Wheater et al., 2011) I can’t resist putting my own personal slant on the subject.

  • The type of habitat can have a marked effect on what you catch. Not all habitats are equally amenable to sweeping; spiny and woody vegetation poses more problems than a nice meadow and you need a really tough net for moorlands 🙂
  • A sweep net doesn’t necessarily give you an accurate picture of the species composition of the habitat. Not all insects are equally catchable, you are for example, much more likely to catch Hemipterans than you are Coleopterans (e.g. Standen, 2000)
  • The vertical distribution of the insects also affects what you catch. Many insects have favourite positions on plants e.g. the cereal aphid, Sitobion avenae prefers the ears and leaves, whereas the bird cherry-oat aphid, Rhopalosiphum padi is usually found at the bottom of the plant (Dean, 1974).
  • The weather; anyone who has tried sweep netting during, or after, a rain storm knows that this is the ultimate act of folly 🙂 Wet nets and wet samples are not a marriage made in heaven.
  • Time of day can also affect what you are likely to catch, pea aphids for example, are found at different heights on their host plants at different times of day (Schotzko & O’Keeffe, 1989). To be fair, this is of course not just a problem confined to sweep net sampling.
  • Sweep nets have a fairly well-defined height range at which they work best, they are not good at sampling very short grass and once the vegetation gets over 30 cm you start to miss a lot of the insects associated with it as the net doesn’t reach that far down. Also the efficiency of the sweep netter is reduced.
  • Finally, how the hell do you standardise your sweeps, not only between sweepers, but as an individual? Additionally, can you reliably use them quantitatively? This has been recognised as a problem for a long time (DeLong, 1932).  No one disagrees that sweep netting, provided all the caveats listed above are taken into account, gives a very good qualitative and comparative idea of the arthropod community of the area you are sweeping and they have been so used in many important ecological studies (e.g. Menhinick, 1964; Elton, 1975; Janzen & Pond, 1975) and extensively in agricultural systems (e.g. Free & Williams, 1979; Kogan & Pitre, 1980).  Comparing any sampling technique with another is difficult, and any attempt to quantify a catch so that specific units can be assigned to the area or volume sampled is welcome.  This has been attempted for the sweep net (Tonkyn, 1980), although I confess that I have never seen anyone use the formula developed by him.  In fact, although, according to Google Scholar his paper has been cited thirteen times, only one of the citing authors actually uses the formula, the rest just use him to cite sweep netting as a sampling method. Poor practice indeed.

An illustration of how the various components of the sweep net volume formula is derived (from Tonkyn, 1980).

Sweep nets are, despite the inability to get inside them anymore, great fun to use, extremely good at collecting material for ecology and entomology practicals and of course, a great ecological survey tool when used properly.  Google Scholar tells me that there are over 38 000 papers that mention them.  That many people can’t possibly be wrong 🙂


Clark, H. (1860) Catalogue of the Collection of Halticidae in the British Museum. Physapodes and Oedipodes Part 1. Published by the Trustees, London.

Dean, G.J. (1974) The four dimensions of cereal aphids. Annals of Applied Biology, 77, 74-78.

DeLong, D.M. (1932) Some problems encountered in the estimation of insect populations by the sweeping method.  Annals of the Entomological Society of America, 25, 13–17.

Douglas, J.W.  (1856) The World of Insects: A Guide to its Wonders. John van Voorst, London.

Douglas, J.W. & Scott, J. (1865) The British Hemiptera Volume I Hemiptera – Heteroptera. Ray Society, Robert Hardwicke, London.

Elton, C.S. (1975) Conservation and the low population density of invertebrates inside neotropical rain forest.  Biological Conservation, 7, 3-15.

Free, J.B. & Williams, I.H. (1979) The distribution of insect pests on crops of oil-seed rape (Brassica napus L.) and the damage they cause. Journal of Agricultural Science, 92, 139-149.

Janzen, D.H. & Pond, C.M. (1975) A comparison, by sweep sampling, of the arthropod fauna of secondary vegetation in Michigan, England and Costa Rica. Transactions of the Royal Entomological Society of London, 127, 33-50.

Kogan, M. & Pitre, H.N. (1980) General sampling methods for above-ground populations of soybean arthropods. Pp 30-60 [In] Sampling Methods in Soybean Entomology. (Eds.) M. Kogan & D.C. Herzog, Springer, New York.

Menhinick, E.F. (1964) A comparison of some species-individuals diversity indices applied to samples of field insects. Ecology 45, 859-861.

Newman, E. (1844) The Zoologist. A Popular Miscellany of Natural History, Volume 2. John van Voorst, London.

Newman, E. (1841) A Familiar Introduction to the History of Insects. John van Voorst, London.

Newman, E. (1835) The Grammar of Entomology. Frederick Westley & A.H. Davis, London.

Schotzko, D.J. & O’Keeffe, L.E. (1989) Comparison of sweep net., D-Vac., and absolute aampling., and diel variation of sweep net sampling estimates in lentils for pea aphid (Homoptera: Aphididae)., Nabids (Hemiptera: Nabidae)., lady beetles (Coleoptera: Coccinellidae)., and lacewings (Neuroptera: Chrysopidae). Journal of Economic Entomology, 82, 491-506.

Southwood, T.R.E. (1966) Ecological Methods, Methuen & Co., London.

Stainton, H.T. (1852) The Entomologist’s Companion; Being a Guide to the Collection of Microlepidoptera and Comprising a Calendar of the British Tineidae. John van Voorst, London.

Standen, V. (2000) The adequacy of collecting techniques for estimating species richness of grassland invertebrates.  Journal of Applied Ecology, 37, 884-893.

Tonkyn, D.W. (1980) The formula for the volume sampled by a sweep net.  Annals of the Entomological Society of America, 73,452-454.

Wheater, P.C., Bell, J.R. & Cook, P.A. (2011) Practical Field Ecology: A Project Guide, Wiley-Blackwell, Oxford.


*Of interest to me, but perhaps not to my readers, Edward Newman was one of the founder members of the oldest and most exclusive, yet low-key, entomological society in the world, The Entomological Club, of which I have the honour of being a member 😊  founder member of the Entomological Club




Filed under Entomological classics

Prunella – mistress of plasticity

Now that I have your attention, this is not an article about soft porn or fetishes, but rather a paean for that humble ‘weed’ Prunella vulgaris – Self-heal, Heal all, Woundwort, Heart of the Earth and many other names, depending on where in the World you come from.   Prunella vulgaris is in the family Lamiaceae, so related to mints and dead-nettles.  It is an edible weed, the young leaves can be used in salads and it can also be used in soups, stews, or used whole and boiled as a pot herb.

The instantly (to me at any rate) recognisable flower of Prunella vulgaris

Prunella as I will now familiarly call her, has a very wide geographical native range and has also been introduced into South America where she does very well indeed (Godoy et al., 2011).

Distribution of Prunella vulgaris, blue native, brown introduced.

 The name Prunella is derived from ‘Brunella’, a word which is itself a derivative, coming from the German name for quinsy, (a type of throat inflammation), die Braüne, which it was historically used to cure.  That is the other aspect of this glorious plant, it has many medicinal properties, hence the many common names refer to its healing powers, almost as many as Athelas of Lord of the Rings fame 😊  It was traditionally used in European herbal medicine for sore throats, fever reduction and like Athelas, for accelerating the healing of wounds (Matthiolus, 1626).  More recently it has become of interest as a possible cure for conditions associated with the herpes simplex virus (Psotováa et al., 2003) and inhibiting anaphylactic shock and other immediate type allergic reactions (Shin et al., 2001).  So truly a wonder drug, and again proving that “Old Wives Tales” are in many cases based on more than just superstition.

My interest in Prunella vulgaris, is however, based on its wondrous plasticity, as the three photographs below show nicely.  Depending on grazing (or mowing) pressure, Prunella can grow to reproductive maturity at heights  ranging from just over 2 cm to just under 30 cm. Truly remarkable.

I am of course, not the first person to be fascinated by this plasticity and the taxonomic and evolutionary ins and outs of this lovely plant (Nelson, 1965; Warwick & Briggs, 1979) but I still find it fascinating, and who knows, perhaps one day I might do some work on it myself 😊

The other thing that I like about Prunella is that she is also provides a living for aphids.  She has her own rare and specific one, Aphis brunellae, but is also kind enough to let a few other species make a living on her, Aphis gossypii, Aphis nasturtiiAulacorthum solani,  Macrosiphum euphorbiae, the ubiquitous Myzus persicae, M. ornatus and Ovatomyzus chamaedrys (Blackman & Eastop, 2006).

Aphis brunellae, rare in the UK – with thanks to the two Bobs for permission to use the photograph.


Finally, you will have noticed that the Prunella aphid is A. brunellae, which is derived from the original name of Prunella (I guess Prunella Scales is happy, she could have been Brunella Scales).  Interestingly, her alter-ego was not removed until fairly recently, her tombstone is shown below.


Blackman, R.L. & Eastop, V.F. (2006) Aphids on the World’s Herbaceous Plants and Shrubs Volume 1 Host Lists and Keys.  Wiley, Oxford.

Godoy, O., Saldaña, A., Fuentes, N., Valladares, F. & Gianoli, E. (2011)  Forests are not immune to plant invasions: phenotypic plasticity and local adaptation allow Prunella vulgaris to colonize a temperate evergreen rainforest. Biological Invasions, 13, 1615-1625.

Matthiolus, P.A. (1626) Kräuterbuch.  Noringberg.

Nelson, A.P. (1965) Taxonomic and evolutionary implications of lawn races in Prunella vulgaris (Labiatae). Brittonia, 17, 160-174.

Psotová, J., Kolá, M., Sousek, J., Ívagera, Z., Vicar, J. &Ulrichová, J. (2003) Biological activities of Prunella vulgaris extract. Phytotherapy Research, 17, 1082-1087.

Shin, T.Y., Kim, Y.K. & Kim, H.M. (2001) inhibition of immediate-type allergic reactions by Prunella vulgaris in a murine model.  Immunopharmacology & Immunotoxicology, 23, 423–435.

Warwick, S.I. & Briggs, D. (1979) The genecology of lawn weeds III. Cultivation experiments with Achillea millefolium L., Bellis perennis L., Plantago lanceolata L., Plantago major L. and Prunella vulgaris L. collected from lawns and contrasting grassland habitats.  New Phytologist, 83, 509-536.



Filed under Science writing, Uncategorized

Pick and mix 11 – Another ten links to look at

I’m still on holiday in France so just a series of links this week.

Links to things I thought interesting (picture is the room door of the Ibis Style hotel we stayed at in Paris)


Is “novelty” holding science back?

Using radio tagging to improve the conservation of stag beetles

How ‘Nature’ keeps us healthy, from potted plants to hiking

How scientists at Rothamsted Research and the University of North Texas have engineered a relative of cabbage to produce fish oil

Agricultural efficiency will feed the world, not dogma

A really interesting article about migration and movement of people

Dave Goulson’s work on pesticide residues in garden plants summarised by plant ecologist Ken Thompson

Using a field journal to strengthen learning

At the risk of seeming big-headed an interesting episode of Entocast

I don’t normally post about birds but after this golden oriole

committed suicide against our patio doors thought that this deserved a mention


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Filed under Pick and mix