Saturday, May 21, 2011

Beetles

There is a story (almost certainly apocryphal) that when the eminent evolutionary biologist J.B.S.Haldane was once asked by a  clergyman what he had learned about the mind of the Creator from his studies of natural history he replied to the effect that “he must have had an inordinate fondness for beetles”. In the unlikely event that the story is true, he would probably have had the vast diversity of beetles that have evolved in tropical rainforests in mind, but we have a lot of beetle species here in Britain, many of them small and not particularly easy to identify.


These, feeding on buttercup pollen, are (I think) raspberry beetles Byturus tomentosus – a familiar garden pest. Just a few feet away from where this photo was taken there was a large patch of wild raspberry on the edge of woodland and I made a mental note not to eat any of its fruit in the coming autumn, as the beetles’ next move will be to lay eggs in the flowers, where the maggots will feed in the developing raspberries.


This second photograph shows how the way in which a photo is lit affects the appearance of some identification features. The top photo was taken with natural light and the wing cases (elytra) of the beetles look fairly smooth. The lower picture, taken using flash, reveals just how hairy these beetles are [double-click on the image]. I guess that’s why they have the specific name tomentosus – which means covered in hairs (a tomentum). Beetles aren’t usually thought of as being very effective pollinators of flowers but a study by Olle Pellmyr in Sweden in 1985 (The Coleopterists Bulletin 39 (4)  341-345) of a closely related species B. ochraceus suggests that this beetle might well be doing rather a good job. Pellmyr studied the gut contents of raspberry beetles and found that almost all the pollen there (identifiable by its surface pattern) came from just one species – in his study, wood avens Geum urbanum, which B. ochraceus feeds on. These raspberry beetles probably have more catholic tastes (although they do seem to like buttercups and those hairy elytra were probably quite capable of transferring pollen that they didn’t eat between buttercup flowers.


When I was a kid in rural Sussex  we used to call all beetles that looked like this ‘blood suckers’. More accurately, they’re soldier beetles (on account of their smart colours, reminiscent of some regiments’ parade uniforms) and the only ‘blood’ they ever taste is that of other insects, which they often hunt on the flower heads of hogweed and similar umbellifers.











I think this is a Cantharis species but I’m not certain which one. Possibly C. livida. “The Creator’s inordinate fondness for beetles” (or more realistically, natural selection’s  inordinate capacity to exploit genetic variation in subtly different ways) has generated a plethora of tricky-to-identify coleopterans.

6 comments:

  1. Your buttercups runneth over with beetles up there! Great shots of the soldier beetle; it's fun watching these climb grasses and take flight from the tops.

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  2. Hi Rob, I suspect it's because the buttercups act as a parabolic reflector - so it's warm in there...

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  3. Smart looking little creatures.

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  4. Yes, you are right. The shape and the colour of the flower must be making it a cosy place for the beetles. The great JBS Haldane lived in India in his last days.

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  5. They are well turned out, Toffeeapple

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  6. Hi Lotusleaf, I've just been reading about Haldane and his life in India - fascinating man..

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