Tag Archives: distribution

Cockroach – an unlikely pairing

Cockroaches, like aphids, tend to get a bad press, the former as objects of disgust, the latter as pests. This is of course because our perception of cockroaches is heavily influenced by the scuttling, slithering and susurrus images that haunt our memories from watching too many reality TV shows and horror films*.

Cockroaches are members of the superorder, Dictyoptera and are placed in the order Blattodea, (derived from the Latin, blatta, an insect that shuns light) which, perhaps somewhat surprisingly, along with the termites (inward et al., 2007).  When I was a student termites had their own Order, Isoptera; molecular biology and DNA studies have a lot to answer for 🙂  There are currently, about 4,600 described species, of which thirty are associated with humans and a mere four which are considered to be pests (Bell et al., 2007); see what I mean about a bad press.  They have a global distribution but are mainly associated with the tropics and sub-tropics.

According to the Oxford English Dictionary (and whom am I to doubt them?), the name “cockroach” comes from the Spanish word cucaracha, transformed by 1620s English folk etymology (where an unfamiliar word is changed into something more familiar) into “cock” (male bird) and “roach” (a freshwater fish).  I find this a little odd.  Given that the Romans were trading globally before they colonised England, it seems unbelievable that the Oriental and German cockroaches would not have made it to the British Isles and become a familiar pest, before the early seventeenth century.  That said, Robinson (1870) suggests that according to Gilbert White the Oriental cockroach Periplaneta orientalis, sometimes called the black beetle (e.g. Blatchley, 1892), was not introduced into England until 1790.  A reference in Packham (2015) however puts its introduction as 1644, which fits better with the OED’s date of derivation of the word.  I would, despite this, still suggest that the Romans would have been the more likely ones to have brought it to our shores.  I think it quite likely that anything that scuttled along the ground and was dark in colour would have been referred to as a black beetle, so my view is that our pestiferous cockroaches have been around much longer.  Any sources to prove/disprove this will be welcome.

Our native cockroaches, as opposed to those that have become naturalised, are shy, retiring, quite rare and located mainly in the south of England, where they dwell peacefully among the trees and heather, a situation that has remained largely unchanged for almost 200 years (Stephens, 1835).  Their names, except for Ectobius pallidus, seem to indicate an origin from farther afield, or perhaps just reflect the origin of the entomologist who first described them  🙂

Ectobius panzeri, The Lesser cockroach (distribution from the NBN Atlas)

Ectobius lapponicus, The Dusky cockroach (Distribution from the NBN Atlas). It is also known as the Forest cockroach in Hungarian   http://regithink.transindex.ro/?p=8782.  According the NBN Atlas it has been recorded as eating aphids.

Ectobius lapponicus showing the wings unfolded.

Ectobius pallidus, the Tawny cockroach (also known as Mediterranean Spotted Cockroach) (Distribution from the NBN Atlas)


Cockroaches, unlike ladybirds and aphids, don’t seem to have amassed a huge number of weird and wonderful names in other languages.  If anyone has some good examples to add, please let me know.

Albanian kakabu

Basque labezomorro (labe = oven, zomorro = bug)

Bulgarian хлебарка khlebarka

Finnish torakka

French  cafard (in English melancholia)

German kakerlake

Hungarian csótány

Italian scarafaggio (sounds like a character from an Opera)

Latin blatta

Latvian prusaku

Polish karaluch

Spanish cucaracha

Swedish kackerlacka

Yiddish tarakan

In terms of aesthetically pleasing versions I found Armenian ծխամորճ and Thai แมลงสาบ the most satisfying, and Japanese definitely the most abrupt  ゴキブリ

And to end,  a fun fact that might make some of you disposed to look more kindly upon the cockroach “The Cockroach is the natural enemy of the bed-bug, and destroys large numbers” (Packard, 1876).



Bell, W.J., Roth, L.M. &  Nalepa,  A.A. (2007) Cockroaches: Ecology, Behavior and Natural History.  The Johns Hopkins University Press, Baltimore.

Blatchley, W.S. (1892) The Blattidae of Indiana.  Proceedings of the Indiana Academy of Science, 1892, 153-165.

Brown, V.K. (1980)  Notes and a key to the Oothecae of the British Ectobius (Dictyoptera: Blattidae).  Entomologist’s Monthly Magazine, 116, 151-154.

Inward, D., Beccaloni, G. & Eggleton, P. (2007) Death of an order: a comprehensive molecular phylogenetic study confirms that termites are eusocial cockroaches. Biology Letters, 3, 331-335.

Packham, C. (2015) Chris Packham’s Wild Side of Town. Bloomsbury Press, London.

Packard, A.P. (1876) Guide to the Study of Insects and a Treatise on those Beneficial and Injurious to Crops. Henry Holt & Company, New York.

Robinson, C.J. (1870) The cockroach.  Nature, 2, 435.

Stephens, J.S. (1835) Illustrations of British Entomology; or a Synopsis of Indigenous Insects. Volume VI. Mandibulata.  Baldwin & Cradock, London.





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Midwinter Madness – The Snow flea

Between 1982 and 1992 I worked as a research and advisory entomologist for the UK Forestry Commission based at their Northern Research Station just outside Edinburgh. For the first five years of my time there I worked almost exclusively on the pine beauty moth, Panolis flammea. The pine beauty moth is

snowflea 1

a native insect that became a pest of a non-native tree, Pinus contorta, then a tree that was widely planted over northern Britain. The majority of planting in Scotland was in the north and this meant that my study sites were in Sutherland and Caithness and Aberdeenshire. My main experimental forest was west of Aberdeen in the Spey valley (very handy for the whisky trail) in the Elchies block of Criagellalchie Forest.

snow flea 2

My experimental forest with nearby distillery marked 😉

In Mid-January 1984, I headed north to do some maintenance on my head capsule collecting funnel traps.

snowflea 3

In those days, snow was a perennial hazard, even in the south of Scotland and as I progressed northwards the drifts at the side of the road became increasingly higher. When I reached the forest gates, it was obvious that I was not going to be able to drive to my site. The sun was shining, the sky was blue and the snow glistened. A perfect day for a walk, albeit one of 10 km. Luckily, the weather had been sunny for the last couple of days so the snow was mostly hard enough to walk on. Only in a few places did I break the surface and find that I was standing on about a metre depth of snow. Two hours later as I was approaching my field site, squinting against the sun bouncing off the white untouched snow, I saw black spots moving on the surface. My immediate thought was that I was suffering the first stages of snow-blindness, but as I got nearer I saw that the black dots were actually insects. At first sight I thought I was hallucinating, was this some strange bizarre form of life perhaps an aphid-fly hybridization experiment gone wrong? On closer examination I realised that I was looking at wingless Mecopterans.

snow flea 4

Male snow flea, Boreus hyemalis http://mecoptera.free.fr/Boreus-hyemalis.html


snow flea 5

Female Boreus hyemalis, note the sting-like ovipositor. http://www.wbrc.org.uk/WORCRECD/32/Bingham–John–Snow_Flea_Boreus_hyemalis.html

Although I was familiar with Scorpion-flies, I had never seen these critters before.

snow flea 6

The aptly named Scorpion fly Panorpa communis : https://commons.wikimedia.org/wiki/File:Scorpion_Fly._Panorpa_communis._Mecoptera_(7837166610).jpg

I collected a few to send off for identification and confirmation and carried on into the depths of the forest to check on my funnels. On returning to civilization a day or so later I sent my specimens off to the Natural History Museum and shortly after was informed that I had they were the snow flea, Boreus hyemalis and that I had extended the recorded range of this particular species, albeit only by a few miles.

snow flea 7

My record – it lasted 10 years as the furthest north before M.S.C. Elliott recorded it in February 1994 in Easter Fearn in the north-west Highlands.

Boreus my record

Distribution of Boreus hyemalis in 1994; my record, then the furthest North.


snow flea 9

Current recorded distribution of Boreus hyemalis – obviously widespread – just lacking people willing to go and look for it in the winter 🙂

So what is a snow flea. It is of course, not a flea, being a Mecopteran or Scorpion fly, albeit non-winged.  In Britain there are three species with wings (in the genus Panorpa), the larvae and adults both being predatory on other insects. The adult snow flea is about 5mm long, and lives among moss on which it feeds as both a larva and adult (Withycombe, 1922, 1926). Interestingly, the BugLife site states that they are predatory in both the larval and adult stage. I am not sure where they got this information as they do not cite a reference and all the published literature I have seen indicates that they are moss feeders (Withycombe, 1922, 1926; Fraser, 1943; Hågvar, 2010). Indeed, Wthycombe (1922) conducted a series of experiments on the larvae and conclusively demonstrated that they were unable to complete their development unless fed on moss, although the adults will apparently also feed on dead insects.

These are true winter-active insects, adults emerging in October and November when they mate and lay their eggs the eggs at the base of moss plants), Polytrichium commune being the preferred host (Fraser, 1943). The eggs start to hatch in November and the larvae forage within the moss clumps, pupating towards the end of the summer, emerging as adults after 6-8 weeks.  The adults, which are wingless, thus come out in the coldest months of the year, usually between October and April.  They are most easily seen when walking or jumping on the snow surface. Considering that the adults are winter-active they have a surprisingly high super-cooling point (-6.5oC) (Sömme & Östbye, 1969), especially when compared with the cereal aphid, Sitobion avenae, which has a super-cooling point of -24oC but rarely survives English winters (Knight & Bale, 1986). The BugLife site wonders “how they (snow fleas) manage to jump up to 5 cm without muscular hind legs” but Burrows (2011) found that their jumping prowess is by virtue of large depressor muscles within the thorax which enables them to jump distances of up to 10 cm with a take-off velocity of 1 m s-1, indicating a force of about 16 times their body weight.  So aptly named in this respect too.

The Snow flea is not found (or at least has not been recorded) in the mild south-west of Britain, seeming to prefer areas with a harsher winter. Climate warming may thus pose a threat for this intriguing and little studied insect. Perhaps it is time for us all to venture out in mid-winter and start scanning the surface of snow drifts in heathland areas for these elusive creatures before it is too late.



Burrows, M (2011) Jumping mechanism and performance of snow fleas (Mecoptera, Boreidae). Journal of Experimental Biology, 214, 2362-2374.

Fraser, F.C. (1943) Ecological and biological notes on Boreus hyemalis (L.) (Mecopt., Boreidae). Journal of the Society for British Entomology, 2, 125-129

Knight, J. D. & Bale, J. S. (1986). Cold hardiness and overwintering of the grain aphid Sitobion avenae. Ecological Entomology 11, 189-197.

Sömme, L. & Östbye, O. (1969) Cold-hardiness in some winter active isnects. Norsk Entomologisk Tidsskrift, 16, 45-48

Withycombe, C. L. (1922). On the life history of Boreus hyemalis L. Transactions of the Entomological Society of London, 1921, 312-318.

Withycombe, C. L. (1926). Additional remarks upon Boreus hyemalis L. Entomologist’s Monthly Magazine, 62, 81-83.


Useful link

For more images and observations see http://www.wbrc.org.uk/WORCRECD/32/Bingham–John–Snow_Flea_Boreus_hyemalis.html



Filed under EntoNotes

Entomological Classics – Southwood 1961 – The number of insect species associated with various trees


Nineteen-Sixty-One  was a momentous  year for entomology and ecology, although at the time I suspect few realised it.  Skip forward to 2013 when The British Ecological Society published a slim volume celebrating  the 100 most influential papers published in the Society’s journals.  The papers included in the booklet were selected based on the opinions of 113 ecologists from around the world, who were then asked to write a short account of why they thought that paper influential.  I was disappointed not to be asked to write about my nomination but instead asked to write about Maurice Solomon’s 1949 paper in which he formalised the term functional response.

The paper I had wanted to write about was included, but John Lawton had the privilege of extolling its virtues, and given the word limits did a pretty good job.  I do, however, feel that given its importance to ecology and entomology it deserves a bit more exposure, so I am taking the opportunity to write about it here.  I could have included this post in a series I have planned, called Ten Papers that Shook My World, but given the impact that this paper has had on entomologists I felt it deserved an entry in my Entomological Classics series.

For those of you who haven’t come across this paper before, this was an astonishingly influential paper.  Basically, Southwood, who despite his later reputation as one of the ecological greats, was an excellent entomologist, (in fact he was a Hemipterist), wanted to explain why some tree species had more insect species associated with them than others.  He made comparisons between trees in Britain, Russia and Cyprus and demonstrated that those trees that were more common and had a wider range had more insect species associated with them (Figure 1).

Southwood 1961 Fig 1

From Southwood 1961.  I was surprised to see that he had committed the cardinal error in his Figure caption of describing it as Graph and also including the regression equation in the figure pane; two things that I constantly reprimand students about!

Importantly he also showed that introduced trees tended to have fewer insects than native species.  He thus hypothesised that the number of insects associated with a tree species was proportional to its recent history and abundance and was a result of encounter rates and evolutionary adaptation.  He then tested this hypothesis using data on the Quaternary records of plant remains from Godwin (1956) making the assumption that these were a proxy for range as well as evolutionary age.

He commented on the outliers above and below the line suggesting that those above the line were a result of having a large number of congeners and those below the line either as being taxonomically isolated and/or very well defended.

He then went on to test his ideas about the evolutionary nature of the relationship by looking at trees and insects in Hawaii, (ironically this appeared in print (Southwood, 1960), before the earlier piece of work (Journal of Animal Ecology obviously had a slower turnaround time in those days than they do now).

Hawaiin figure

Figure 2.  Relationship between tree abundance and number of insect species associated with them (drawn using data from Southwood 1960).

Considering the research that these two papers stimulated over the next couple of decades, what I find really odd, is that Southwood, despite the fact that he was dealing with data from islands and that Darlington (1943) had published a paper on carabids on islands and mountains in which he discussed species-area relationships and further elaborated on in his fantastic book (Darlington, 1957), did not seem to see the possibility of using the species-area concept to explain his results.  It was left to Dan Janzen who in 1968 wrote

It is unfortunate that the data on insect-host plant relationships have not in general been collected in a manner facilitating analysis by MacArthur and Wilson’s methods (as is the case as well with most island biogeographical data). What we seem to need are lists of the insect species on various related and unrelated host plants, similarity measures between these lists (just as in Holloway and Jardine’s 1968 numerical taxonomic study of Indo- Australian islands), knowledge of the rates of buildup of all phytophagous insect species on a host plant new to a region, where these species come from, etc. Obviously, the insect fauna must be well known for such an activity. The English countryside might be such a place; it has few “islands” (making replication difficult) but a very interesting “island” diversity, with such plants as oaks being like very large islands and beeches being like very small ones, if the equilibrium number of species on a host plant (Elton, 1966; Southwood, 1960) is any measure of island size.”


In 1973 Dan Janzen  returned to the subject of trees as islands and cited Paul Opler’s 1974 paper in relation to the fact that the number of  herbivorous insects associated with a plant increases with the size of the host plant population (Figure 3), and further reiterated

Opler Figure

Figure 3.  Opler’s 1974 graph showing relationship between range of oak trees in the USA and the number of herbivorous insect species associated with them.

 his point about being able to consider trees as ecological islands.  Opler’s 1974 paper is also interesting in that he suggested that this approach could be used for predicting pest problems in agricultural systems, something that Don Strong and colleagues did indeed do (Strong et al., 1977; Rey et al., 1981), and that the concept of habitat islands and the species-area relationship could be used when designing and evaluating nature reserves, something which indeed has come to pass.

Again in 1974 but I think that Strong has precedence because Opler cites him in his 1974 paper, Don Strong reanalysed Southwood’s 1961 data using tree range (based on the Atlas of the British Flora)  as the explanatory variable  (figure 4) to explain the patterns seen.

Strong Figure

Figure 4Strong’s reworking of Southwood’s 1961 insect data using the distribution of British trees as shown in Perring & Walters1 (1962).

The publication of this paper opened the floodgates, and papers examining the species-area relationships of different insect groups and plant communities proliferated (e.g  leafhoppers (Claridge & Wilson, 1976); bracken (Rigby & Lawton, 1981); leaf miners (Claridge & Wilson, 1982); rosebay willow herb (McGarvin, 1982), with even me making my own modest contribution in relation to Rosaceous plants   (Leather, 1985, 1986).

Although not nearly as popular a subject as it was in the 1980s, people are still extending and refining the concept  (e.g. Brändle & Brandl, 2001; Sugiura, 2010; Baje et al., 2014).

Southwood (1961) inspired at least two generations of entomologists and ecologists, including me, and is still relevant today.  It is truly an entomological (and ecological) classic.


Baje, L., Stewart, A.J.A. & Novotny, V. (2014)  Mesophyll cell-sucking herbivores (Cicadellidae: Typhlocybinae) on rainforest trees in Papua New Guinea: local and regional diversity of a taxonomically unexplored guild.  Ecological Entomology 39: 325-333

Brändle, M. &Brandl, R. (2001). Species richness of insects and mites on trees: expanding Southwood. Journal of Animal Ecology 70: 491-504.

Claridge, M. F. &Wilson, M. R. (1976). Diversity and distribution patterns of some mesophyll-feeding leafhoppers of temperate trees. Ecological Entomology 1: 231-250.

Claridge, M. F. &Wilson, M. R. (1982). Insect herbivore guilds and species-area relationships: leafminers on British trees. Ecological Entomology 7: 19-30.

Darlington, P. J. (1943). Carabidae of mountains and islands: data on the evolution of isolated faunas and on atrophy of wings. Ecological Monographs 13: 37-61.

Darlington, P. J. (1957). Zoogeography: The Geographical Distribution of Animals. New York: John Wiley & Sons Inc.

Elton, C. S. (1966). The Pattern of Animal Communities. Wiley, New York.

Holloway, J. D., & Jardine, N. (1968). Two approaches to zoogeography: a study based on the distributions of butterflies, birds and bats in the Indo-Australian area. Proceedings of the Linnaean Society. (London) 179:153-188.

MacArthur, R. H. & Wilson, E.O. (1967). The Theory of Island Biogeography. Princeton University Press, Princeton, N. J

Janzen, D. H. (1968). Host plants as islands in evolutionary and contemporary time. American Naturalist 102: 592-595.

Janzen, D. H. (1973). Host plants as islands II.  Competitive in evolutionary and contemporary time. American Naturalist 107: 786-790.

Kennedy, C.E.J. & Southwood, T.R.E. (1984) The number of species of insects associated with British trees: a re-analysis. Journal of Animal Ecology 53: 455-478.

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 hostrange, plant architecture, age of establishment, taxonomic isolation and species-area relationships. Journal of Animal Ecology 55: 841-860.

Macgarvin, M. (1982). Species-area relationships of insects on host plants: herbivores on rosebay willowherbs. Journal of Animal Ecology 51: 207-223.

Opler, P. A. (1974). Oaks as evolutionary islands for leaf-mining insects. American Scientist 62: 67-73.

Perring, F.J. & Walters, S.M. (1962) Atlas of the British Flora BSBI Nelson, London & Edinburgh.

Preston,  C.D., Pearman, D.A. & Tines, T.D. (2002) New Atlas of the British and Irish Flora: An Atlas of the Vascular Plants of Britain, Ireland, The Isle of Man and the Channel Islands. BSBI, Oxford University Press

Rigby, C. & Lawton, J. H. (1981). Species-area relationships of arthropods on host plants: herbivores on bracken. Journal of Biogeography 8: 125-133.

Solomon, M. E. (1949). The natural control of animal populations. Journal of Animal Ecology 18: 1-35

Southwood, T. R. E. (1960). The abundance of the Hawaiian trees and the number of their associated insect species. Proceedings of the Hawaiian Entomological Society 17: 299-303.

Southwood, T. R. E. (1961). The number of species of insect associated with various trees. Journal of Animal Ecology 30: 1-8.

Sugiura, S. (2010). Associations of leaf miners and leaf gallers with island plants of different residency histories.  Journal of Biogeograpgy 37: 237-244

Rey, J.R.M.E.D. & Strong, D.R. (1981) Herbivore pests, habitat islands, and the species area relation. American Naturalist 117: 611-622.

Strong, D. R. (1974). The insects of British trees: community equilibrium in ecological time. Annals of the Missouri Botanical Gardens 61: 692-701.

Strong, D.R., D., M.E., & Rey, J.R. (1977) Time and the number of herbivore species: the pests of sugarcane. Ecology 58: 167-175



The Atlas of the British Flora by Perring and Walters (1962) was an iconic piece of work, although not without its flaws.  As with many distribution atlases it is based on a pence or absence score of plant species within one kilometre squares.  So although it is a good proxy or range it does not necessarily give you an entirely reliable figure for abundance.  A dot could represent a single specimen or several thousand specimens.   Later authors attempted to correct for this by using more detailed local surveys e.g. tetrads.  It must have been particularly galling for  Southwood that the Atlas didn’t appear until after he had published his seminal papers, but he later made up for it by reanalysing and extending his data from that original 1961 paper (Kennedy et al., 1984).

Those of us working in this area using the original Atlas had to count the dots by hand, a real labour of love especially for those widely distributed species; the new edition (Preston et al., 2002) actually tells you how many dots there are so the task for the modern-day insect-plant species-area relationship worker is much easier 😉


Filed under Entomological classics, EntoNotes, Ten Papers That Shook My World