Dear Readers, I was so entranced by these beetles yesterday that I thought I’d seek out a little more information to share with you all. I have seen the common name vary between Thick-thighed beetle, Swollen-thighed beetle and Thick-legged beetle, so hooray for scientific nomenclature, because all of these titles relate to Oedemera nobilis, a false blister beetle in the family Oedemeridae. According to the charity Buglife, they are a fair-weather beetle, usually seen nibbling pollen from open-faced flowers such as ox-eye daisies or yarrow or hogweed. Only the males have those impressive thighs and they remain a bit of an enigma – the males beetles don’t jump, or burrow, or even perform some Coleopteran variation on a Cossack dance. I did notice the sun positively glinting off of these appendages, though, so maybe they are just there to impress the ladies. There is also a theory that the thighs are used to grip on to the female beetles during mating, but then most male beetles get on very well without such enhancements. Maybe it’s one of those things that’s not harmful and so persists.
Incidentally I didn’t see a single female, so maybe the thighs aren’t all that attractive after all. Here is a photo just so that you can compare.
It’s easy to forget that beetles can fly, and when I was watching these beetles I was mildly surprised when one of them flipped open his wing-cases and bumbled over to the next hogweed flower. It’s certainly a lot easier than going down to the ground, running over the soil and then climbing up the next stem. A thick-legged flower beetle seems to have a rather idyllic life, feeding on pollen and nectar and then drifting over to the next plant. The young live in the hollow plant stems of flowers such as thistles, another reason not to be in too much of a hurry to cut back your ‘weeds’ when they’ve finished flowering.
And if you’ll forgive me another brief digression, I was surprised when I really looked at the flowers of the hogweed to see that they aren’t a mass of symmetrical daisy-like flowers at all – each individual flower looks very wonky, rather like someone in a white-flared body suit. I’m guessing that this is one way of fitting the maximum number of small flowers onto one flowerhead, but who knows?
All members of the Oedemeridae contain cantharidin, otherwise known as Spanish fly – this is a defensive substance which deters predators from eating them, and may be why they can display such fine metallic colours without having to worry about being detected. If handled, the beetles can exude a fluid which irritates and blisters the skin, one reason for the family name being ‘False Blister Beetle’. I’m not sure what the ‘false’ bit refers to though, as it appears that the blisters are very real. However, some naturalists are trying to rename the family as ‘pollen beetles’, which is an adept piece of public relations for sure ( and descriptive, because as adults they eat nothing but pollen and the odd sip of nectar).
Doing my cemetery walk every week has proved to be a fascinating calendar of what appears when – last week I didn’t see a single one of these beetles, but this week they’re everywhere. Or maybe I just didn’t look closely enough? The world certainly becomes a richer place when we spare a few minutes to really look at things.