Tag Archives: sycamore aphids

Ideas I had and never followed up

“When I was younger, so much younger than before” I never needed any help to come up with ideas for research topics or papers.   When I was doing my PhD and later as a post-doc, I used to keep a note pad next to my bed so that when I woke up in the middle of night with an idea (which I often did) I could scribble it down and go back to sleep.  (These days sadly, it is my bladder and not ideas that wake me up in the wee small hours 🙂*)

On waking up properly, these ideas, if they still seemed sensible, would  move onto Stage 2, the literature search.  In those days, this was much more difficult than it is now, no Google Scholar or Web of Science then, instead you had to wade though the many hard-copy Abstract series and then get hard copies of the papers of interest.  Once in my hands, either via Inter-library loans or direct from the author, or even photocopied from the journal issue (we did have photocopiers in those days), the papers would be shoved into a handy see-through plastic folder (Stage 3).  Depending on how enthusiastic I was about the idea, I would then either mock-up a paper title page or put the folder in the ‘to deal with later’ pile (Stage 4).   Many of these eventually led on to Stage 5, experiments and published papers.  Others have languished in their folders for twenty or thirty years.

As part of my phased run up to retirement (2021), I have started farming out my long-term publishable (hopefully) data-sets to younger, more statistically astute colleagues and ‘publishing’ less robust, but possibly useful data on my blog site.  I have also, somewhat halfheartedly since the task is monumental, started to go through my old field and lab books that


A monumental collection of data.  The top right picture is my 20-year sycamore data set.  I estimate that there are about 7 million data points in it; of which to date only 1.6 million, give or take a million, are computerised.  I also have a ten-year bird cherry aphid data set from Scotland, waiting to go on the computer, any volunteers?

are not yet computerised.  Whilst doing this I came across some Stage 3 folders, which as you can see from the colour of the paper have languished for some time.


The Forgotten Nine


There were nine forgotten/dismissed proto-papers, the oldest of which, judging by the browning of the paper and my corresponding address, dates from the early 1980s, and is simply titled “What are the costs of reproduction?”.  This appears to have been inspired by a talk given by Graham Bell at a British Ecological Society, Mathematical Ecology Group meeting in 1983.  In case you are wondering, this was one of those meetings supposed to bring theorists and empiricists together.   It didn’t work, neither group felt able to talk to each other 🙂  The idea, inevitably based on aphid data, didn’t bear any fruit, although I do have this graph as a souvenir.  If anyone wants


In those days we used graph paper 🙂

 the data, do let me know.

Slightly later, we find the grandly titled, “Size and phylogeny – factors affecting covariation in the life history traits of aphids”.  This had apparently been worked up from an earlier version of a paper, less grandly, but no less ponderously, titled, “Size and weight: factors affecting the level of reproductive investment in aphids”.  This is based on some basic dissection data from eight aphid species and presents the relationships, or lack of, between adult weight (or surrogate measure), ovariole number, potential fecundity and the number of pigmented embryos.  As far as I can remember these are data that Paul Wellings** and I collected as a follow-up to work we had published from a side project when we were doing our PhDs at the University of East Anglia (Wellings et al., 1980).  The second title was inspired by a paper by Stephen Stearns (Stearns, 1984), who was something of a hero of mine at the time, and was, I guess, an attempt to publish pretty simple data somewhere classier than it deserved 🙂  So this one seems to be a Stage 4, almost Stage 5 idea, and may, if I have time or someone volunteers, actually get published, although I suspect it may only make it to a very minor journal under its original title.

Then we have a real oddity, “Aphids, elephants and oaks: life history strategies re-examined”.  This one as far as I remember, is based on an idea that I had about r- and k-selection being looked at from a human point of view and not the organism’s point of view.  My thesis was that an oak tree was actually r-selected as over its life-time it was more fecund than an aphid 🙂  I suspect this was going to be aimed at the Forum section of Oikos.

The next one, dates from the late-1980s, “Protandry versus protogyny: patterns of occurrence within the Lepidoptera”, and reflects the fact that females of the pine beauty moth, Panolis flammea, on which I was then working, emerge before the males (Leather & Barbour, 1983; Leather, 1984), something not often reported in Lepidoptera.  I wondered what advantage (if any) this gave P. flammea.  I planned this one as a review or forum type paper but never got beyond the title and collecting two references (Robertson, 1987; Zonneveld & Metz, 1991).  I still think this is an interesting idea, but do feel free to have a go yourselves, as again, I suspect that I won’t actually get round to it.

Finishing off my time in Scotland, is a paper simply entitled, “Egg hatch in the bird cherry aphid, Rhopalosiphum padi.” I have ten years of egg hatch data from eight trees waiting to be analysed.  This is almost certainly not worth more than a short note unless I (or a willing volunteer) tie it in with the ten years data on spring and autumn populations on the same trees 🙂 Aphid egg data although not very abundant, is probably not in great demand.  My first published paper (Leather, 1980) was about egg mortality in the bird cherry aphid and 36 years later has only managed to accrue 32 citations, so I guess not an area where one is likely to become famous 🙂

I then have four papers dating from my time as an Associate Member of the NERC Centre for Population Biology at Silwood Park.   The first is titled, “The suitability of British Prunus species as insect host plants” and was definitely inspired by my foray into counting host plant dots as exemplified by the late great Richard Southwood (Leather, 1985, 1986).  I think I was going to look at palatability measures of some sort.

The next is called ‘Realising their full potential: is it important and how many insects achieve it?”  I’m guessing that this was a sort of follow-up to my second most-cited paper ever (Leather, 1988), the story of which you can read here, if at all interested.  Most insects, even those that are pests, die before achieving anywhere near their full reproductive potential, but then so do we humans, and our population continues to grow.  So in answer to the question, I guess not and no it doesn’t matter 🙂

Also linked to insect reproduction is the next paper, which I have followed up with the help of a PhD student, and do hope to submit in the near future, “Queue positions, do they matter”.  As this one may actually see the light of day, I won’t say anything further about it.

And finally, another one about aphid eggs, “Bud burst and egg hatch synchrony in aphids”.  This one was going to be based on my then ten-year sycamore aphid data but is now based on my twenty-year data set and is now in the very capable hands of a PhD student and hopefully will see the light of day next year.

There are also a number of other folders with no titles that are just full of collections of reprints.  I can only guess at what these ideas were so won’t burden you with them.

I mentioned at the beginning of this piece that I don’t wake up in the middle of the night with ideas any more.  As we get older I think there is a tendency to worry that we might run out of ideas, especially when, as we do in the UK, suffer from ludicrously underfunded research councils with very high rejection rates that don’t allow you to resubmit failed grant applications.  It was thus reassuring to see this recent paper that suggests that all is not lost after you hit the grand old age of 30.  That said, I do believe that as you move away from the bench or field, the opportunity to be struck by what you see, does inevitably reduce.  As a PhD student and post-doc you are busy doing whatever it is you do, in my case as an ecological entomologist, counting things, and inevitably you see other things going on within and around your study system, that spark off other ideas.  It was the fear of losing these opportunities as I moved up the academic ladder, which inevitably means, less field and bench time and more time writing grant applications and sitting on committees, that I specifically set aside Monday mornings (very early mornings) to my bird cherry plots and even earlier Thursday mornings to survey my sycamore trees.   Without those sacrosanct mornings I am pretty certain I would have totally lost sight of what is humanly possible to do as a PhD student or post-doc.  This, thankfully for my research group, means that I had, and have, realistic expectations of what their output should be, thus reducing stress levels all round.   As a side benefit I got to go out in the fresh air at least twice a week and do some exercise and at the same time see the wonderful things that were going on around and about my study areas and as a bonus had the chance to get some new ideas.



Leather, S.R. (1984) Factors affecting pupal survival and eclosion in the pine beauty moth, Panolis flammea (D&S). Oecologia, 63, 75-79.

Leather, S.R. (1985) Does the bird cherry have its ‘fair share’ of insect pests ? An appraisal of the species-area relationships of the phytophagous insects associated with British Prunus species. Ecological Entomology, 10, 43-56.

Leather, S.R. (1986) Insect species richness of the British Rosaceae: the importance of host range, plant architecture, age of establishment, taxonomic isolation and species-area relationships. Journal of Animal Ecology, 55, 841-860.

Leather, S.R. (1988) Size, reproductive potential and fecundity in insects: Things aren’t as simple as they seem. Oikos, 51, 386-389.

Leather, S.R. & Barbour, D.A. (1983) The effect of temperature on the emergence of pine beauty moth, Panolis flammea Schiff. Zeitschrift fur Angewandte Entomologie, 96, 445-448.

Robertson, H.G. (1987) Oviposition and site selection in Cactoblastis cactorum (Lepidoptera): constraints and compromises. Oecologia, 73, 601-608.

Stearns, S.C. (1984) The effects of size and phylogeny on patterns of covariation inthe life history traits of lizards and snakes. American Naturalist, 123, 56-72.

Wellings, P.W., Leather , S.R., & Dixon, A.F.G. (1980) Seasonal variation in reproductive potential: a programmed feature of aphid life cycles. Journal of Animal Ecology, 49, 975-985.

Zonneveld, C. & Metz, J.A.J. (1991) Models on butterfly protandry – virgin females are at risk to die. Theoretical  Population Biology, 40, 308-321.


*I hasten to add that I do still have new ideas, they just don’t seem to wake me up any more 🙂

**Now Vice-Chancellor of the University of Wollongong



Filed under Science writing, Uncategorized

Getting a buzz with science communication – Reflections on curating Realscientists for a week

My week on Realscientists was a direct result of National Insect Week, a biennial event organised by the Royal Entomological Society (RES) to bring the wonders of entomology to a wider audience*. I had never thought about being a curator for Realscientists although I have followed them for some time.  Back in February however, one of my PhD students who has been involved with National Insect Week on more than one occasion, suggested that I might apply to curate RealScientists during National Insect Week as the RES Director of Outreach, Luke Tilley, was hoping to be on Biotweeps during National Insect Week as well.  To make sure that I had no excuse to forget to do it, she very helpfully sent me the link to the Realscientists web site and instructions on how to apply 🙂

Duly briefed, I contacted Realscientists and to my surprise and slight apprehension, was given the slot I had asked for, the week beginning 19th June.  As my curatorial stint drew closer I began to worry about what I was going to tweet about and how to fit it into my day-to-day activities.

I made a list of twenty pre-planned Tweets to give me an outline script to work from. I managed to include all but one into my week as curator, the one about why you should want to work in entomology.


The twenty tweet list

I felt that my whole week was addressing this point so there was no need to belabour the point any more.  I also received an email from Realscientists with a Vade Mecum of how and what to tweet.  I was somewhat concerned by the section on how to deal with trolling, but I needn’t have worried, as far as I could tell I received no overt abuse**.

The big day approached, which as my actual launch was at Sunday lunchtime caused some slight logistical problems, but easily solved by making lunch a bit later than usual. As it was a Sunday I basically kept it light, introduced myself and tweeted a few insect factoids and pictures, including some great images from van Bruyssels The Population of an Old Pear Tree.  I have my own hard copy of the 1868 translated edition, but if you want to read it on-line it is available here.


From van Bruyssel – The Population of an Old Pear Tree

It is definitely worth a read.

I also had to make a decision about how much time I was going to spend Tweeting. The previous curator had only done about 10-15 tweets a day, which is what I usually do.  The curator before her, however, had done considerably more.  As my stint as curator coincided with National Insect Week and as my contract with my university does actually specify that I do outreach***, I felt that I could justify several hours a day to it and that is what I did, and managing to fit quite a bit of the day job in between.

In between tweeting images and fantastic insect facts I tried to get some important messages across to my audience.  I started with what some might  term a “conservation rant”, basically bemoaning the fact that although insects make up the majority of the animal kingdom, conservation research and funding is very much biased toward the vertebrates, largely those with fur and feathers.  I also pointed out that most statements about how we should go about conservation in general is based on this unbalanced and not very representative research.  Taxonomic chauvinism has annoyed my for a long time 🙂


That rant over I introduced my audience to the work our research group does, biological control, chemical ecology, integrated pest management, agro-ecology and urban ecology and conservation. Our use of fluorescent dust and radio tagging to understand insect behaviour aroused a lot of interest and comment.


Using alternative technology to understand vine weevil behaviour.


The glow in the dark sycamore aphid was also very popular


Midweek I translated one of my outreach talks to Twitter and in a frenzy of Tweets introduced the world to Bracknell and the biodiversity to be found on its roundabouts and how an idea of how to teach locally relevant island biogeography and conservation, turned into a 12 year research project.


How teaching led research – the Bracknell roundabout story.

In between these two main endeavours, I tweeted about the influences that entomology has had on art, literature, popular culture, religion, medicine, engineering, advertising, economics, medicine , fashion and even advertising, using a variety of images.


Our new insect-inspired smoke detector attracted a lot of love and envy.

I even composed a haiku for the occasion

Six-legged creatures;

Fascinating and diverse,

Beautiful insects



I have been an entomologist for a long time.

and told the story of my life-long love of insects, incidentally revealing some of my past hair-styles and exposing my lack of interest in sartorial elegance 🙂

My overall message for the week was, and hopefully I got this across, is that we should be much


more aware of what is under our feet and surrounding us and of course, that aphids are not just fantastic insects


My final tweet

but also beautiful animals.

Giant Myzus

Model Myzus persicae that I recently met in the Natural History Museum

And finally, would I do it again? Yes most definitely. I ‘met’ a lot of new and very interesting people and had some really good ‘conversations’.



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

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

Leather, S. R. (2009). Taxonomic chauvinism threatens the future of entomology. Biologist 56, 10-13.



*I was one of the original ‘founders’ of National Insect Week so have always tried to be involved in some way with the event.

**or I am so thick-skinned I didn’t notice it 🙂

***or as Harper Adams University quaintly terms it, “reach out”





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Filed under EntoNotes, Teaching matters

Serious Fun with Google Trends

No doubt I am behind the curve, but I have only recently discovered Google Trends; a result of attending a Departmental seminar given by a colleague talking about Biochar!

To quote WikipediaGoogle Trends is a public web facility of Google Inc., based on Google Search, that shows how often a particular search-term is entered relative to the total search-volume across various regions of the world, and in various languages. The horizontal axis of the main graph represents time (starting from 2004), and the vertical is how often a term is searched for relative to the total number of searches, globally.”  I was greatly taken by my colleague’s slide showing the birth and development of a new concept


and wondered if this would be a useful tool to look at some entomological topics.  Immediately after the seminar I rushed back to my office, and as you may have guessed, entered the word “aphid” into the search bar and was, after a bit of computer chuntering, rewarded with my first Google Trend output  🙂



I was immediately struck by how closely this resembled real aphid population


data, albeit a more regular and smoother than these examples of real  data.  I found that if you ran the cursor along the data lines the month was displayed, and as I expected, the peak in aphid interest was generally June and May, reflecting their peak abundance in the field.   I next entered


“Ladybird” to see if it coincided with aphid peaks and interestingly found that it had two peaks within each year, May, when they start to become active and October when they start to look for hibernation sites, so as with aphids, the frequency of the search term usage reflects biological activity.  “Butterfly” and “Ant” as search terms revealed that interest in ants and butterflies has remained


fairly constant over the last decade or so, although somewhat to my surprise, ants have had proportionately more searches than butterflies.  Given my worries about the declining interest in plant sciences and the funding problems facing


entomology, I thought it might be educational to compare botany and entomology.

Not an encouraging picture, although at least the decline has plateaued out.  Then, just in case, as in many universities, Botany departments have been replaced with Plant Science departments, and is now taught under that title,


I substituted “Plant Science” for “Botany” and was surprised to see that “Entomology” was searched for about twice as many times as “Plant Science”.

Comparing “Botany” with “Plant Science” reveals that “Botany” was searched for considerably far more than “Plant Science”, despite most universities no longer having Botany Departments. Perhaps they should reconsider their decision to do away with the title?


Keeping with the subject theme and having written in the past about how molecular biology has gained funding and kudos at the expense of whole organism biology (Leather & Quicke, 2010) I compared “Entomology” with


“Botany” and “Molecular Biology” to find, that although overall “Molecular Biology” beats both subjects, interest in the subject has also declined over the last decade. One of my bugbears is the amount of interest and funding that the so called “charismatic mega-fauna” gain at the expense of, in my opinion, the much more deserving invertebrates.


I therefore compared “Giant Panda”, with “Insect” and “Entomology” and was pleasantly surprised to see that “Insect” wasn’t quite overshadowed by “Giant Panda” although somewhat saddened to see that the whole discipline of “Entomology” was not overly popular.

I confess that felt a little frisson of delight when I found that in recent years “Asian giant hornet” has been giving the “Giant panda” a bit of competition 🙂



Recently there has been huge debate over the use of neonicotinoids and their possible/probably part they may have in the decline of bees of all sorts (Jeff Ollerton’s blog is a good place to follow the latest news about the debate), so I used “Bee” “Bumblebee” and “Neonicitinoid” as search terms and was


surprised to find that “Neonicitinoid” in this context has not really had an impact, although if you search for “Neonicitinoid” by itself you



can see that there is an increasing interest in the topic.  A corollary to the banning of pesticides or a call for a reduction in their usage as outlined by the EU Sustainable Use Directive, should be an increased interest in the use of alternative pest control methods, such as


This does not, however, appear to be the case, with interest in biological control and IPM being at their highest in 2004-2006 and despite the ‘neonictinoid debate’ no signs of interest increasing, which is something to puzzle about.

It appears that there is definitely something to be learnt from using Google Trends, although it would be more useful if some indication of the actual number of searches could be made available.  A word of caution, make sure that your search term is well defined, for


example a general search using “butterfly” will give you results for the swimming stroke as well as for the insects.

Although you can compare different geographical regions, and also see the figures for related searches,  what does seem to be lacking,


or perhaps I have been unable to find it, is a way to compare different locations at the same time on the same graph.

I would be very interested to hear from any of you who have used this already and also from any of you who are inspired to use this by my post.  Please do feel free to comment.  Have fun!


Estay, S.A., Lima, M., Labra, F.A., & Harrington, R. (2012) Increased outbreak frequency associated with changes in the dynamic behavour of populations of two aphid species. Oikos, 121, 614-622.

Leather, S. R. & Quicke, D. L. J. (2010). Do shifting baselines in natural history knowledge threaten the environment? Environmentalist 30, 1-2.


Filed under EntoNotes, Uncategorized

Not all aphids have wings

Given that aphids are commonly known as green-fly or black-fly, it might be presumed that all aphids are capable of flight. Although this is almost certainly universal at the species level (but see Post script) it is not true within a species. As I have described in an earlier post aphids are possessed of extremely complex and fascinating (to me at least) life cycles. Depending on the species, either most stages of the life cycle are winged (alate) as adults, e.g. the sycamore aphid Drepanoisphum platanoidis


Sycamore aphid

I couldn’t resist showing you this beautiful picture of an adult sycamore aphid borrowed from the best aphid web site that I know of (see http://influentialpoints.com/Gallery/Drepanosiphum_platanoidis_common_sycamore_aphids.htm)


Other aphid species, such as my favourite, the bird cherry-oat aphid, Rhopalosiphum padi, only produce alate morphs at specific times of year or in response to changes in host plant quality or crowding.


 RhopalosiphumPadi  Rhopalosiphum padi on leaf

Winged (alate) and non-winged (apterous) morphs of Rhopalosiphum padi.

In species such as the sycamore aphid, the only apterous morph tends to be the sexual female or ovipara, which has no need to disperse and after mating lives only long enough to develop and lay its eggs on the bark of sycamore trees.

Sycamore ovip on bark

Ovipara of the sycamore aphid searching for an oviposition site

In those species such as the bird cherry-oat aphid, the winged forms are very different from the non-winged forms, not just in terms of their wings but in their physiology, behaviour and life history traits (Dixon, 1998). The role of the winged morphs is to find new host plants and to start new colonies. They have long antenna, long legs and well-developed and many, sensory organs (rhinaria). They are the dispersal stage, or in the case of winged males, the mate seekers. They respond more readily to host odours; they need to be able to find new host plants at a suitable physiological stage and preferably free of natural enemies. A well-developed olfactory system is thus called for.

If you cut them open (preferably anaesthetizing them first), and remove their ovaries, you will find that they have ovarioles with only a few embryos in each chain and that most of the embryos are not mature i.e. without eye spots. In addition, if you cut open a number of individuals from the same clone you will find that they will not all have the same number of ovarioles. For example, the alate exules (winged forms produced on the secondary host plants )of Rhoaplosiphum padi, the number of ovarioles can range from four to ten (Wellings et al, 1980). This variability of ovariole number in the dispersal morphs of aphids that spend much of their life cycle on ephemeral host plants is quite common (Leather et al 1988).  So why do so many aphid species have variable numbers of ovarioles in their alate morphs?

Shaw (1970), showed that there appeared to be three types of black bean aphid (Aphis fabae) alate exules; migrants, those that flew before depositing nymphs, flyers, those that deposited a few nymphs before flying, and non-flyers, those that stayed and reproduced on their host plant. He postulated that this was an adaptation in response to host quality, the worse state the plant was in the more likely the migrant morph would be produced. Many years later Keith Walters and Tony Dixon (Walters & Dixon, 1983) were able to show that there was a very strong relationship between reproductive investment (number of ovarioles) and flight willingness and ability. The more ovarioles an aphid had, the less likely it was to want to take off and fly, and in addition those with more ovarioles could not fly for as long or as far as those with fewer.

Ovarioles and flight

In other words a trade-off between fecundity and migration. As long distance aphid migration is very costly (very few survive, Ward et al, 1998) it makes sense to have members of your clone spreading the load (risk), from short-distance hops (trivial flights), with the chance that the next door plant might be just as bad as the one left behind and within easy reach of natural enemies, but with a higher chance of survival and reproduction, to long distance migratory flights, with the reduced probability of finding a host plant but with the chance that it will be high in nutrition and low in natural enemies.

What clever beasts aphids are 😉



Dixon, A.F.G. (1998) Aphid Ecology, Second edn. Chapman & Hall, London.

Leather, S.R., Wellings, P.W., & Walters, K.F.A. (1988) Variation in ovariole number within the Aphidoidea. Journal of Natural History, 22, 381-393.

Shaw, M.J.P. (1970) Effects of population density on the alienicolae of Aphis fabae Scop.II The effects of crowding on the expression of migratory urge among alatae in the laboratory. Annals of Applied Biology, 65, 197-203.

Walters, K.F.A. & Dixon, A.F.G. (1983) Migratory urge and reproductive investment in aphids: variation within clones. Oecologia, 58, 70-75.

Ward, S.A., Leather, S.R., Pickup, J., & Harrington, R. (1998) Mortality during dispersal and the cost of host-specificity in parasites: how many aphids find hosts? Journal of Animal Ecology, 67, 763-773.

Wellings, P.W., Leather , S.R., & Dixon, A.F.G. (1980) Seasonal variation in reproductive potential: a programmed feature of aphid life cycles. Journal of Animal Ecology, 49, 975-985.


Post script

It is possible that there are some aphids that never fly – Aphids from the genus Stomaphis have incredibly long mouthparts (they all feed through tree bark), and as far as I can tell from perusal of

Stomaphis query aceris

Roger Blackman and Vic Eastop’s monumental work, alate morphs have never been described (or seen) and even males are apterous.

Blackman, R.L. & Eastop, V.F. (1994) Aphids on the World’s Trees. CABI, Wallingford.


Post post script

For a very detailed and thoughtful review of the ‘decisions’ and costs involved in aphid reproductive and dispersal biology see Ward, S.A. & Dixon, A.F.G. (1984) Spreading the risk, and the evolution of mixed strategies: seasonal variation in aphid reproductive strategies. Advances in Invertebrate Reproduction, 3, 367-386.



Filed under Aphidology, Aphids