Saturday, August 11, 2012

Shagweed -- a Saturday reprise

(It's that time of the year again.)

Another little natural history excursion this morning.

In August, the hedgerows along our bothareen (little road) become botanical gardens to rival Kew. Montbretia, fuchsia, meadowsweet, loosestrife, bramble, bell flower, herb Robert, clover, purple vetch: A glorious display. And there amidst the splendor, the giant hogweed, an ugly, unwelcome interloper, a swaggering oaf among the genteel masses.

But never mind, the hogweed can be interesting too, in particular in that its broad white umbrels are invariably covered with dozens of common red soldier beetles, Rhagonycha fulva, about the size and shape of the American firefly. This past week I noticed that almost every beetle on the plants was paired off, male mounted on female, going at it doggie style.

I lingered to see how long these copulations might last. Indefinitely, it seems. No pair desisted while I watched. They went about their business of feeding on the blossoms locked in a lover's embrace.

One big Roman orgy of beetle sex.

When I got home I went to the internet to find out more about what was going on and discovered that this randy species is commonly known in Britain and Ireland as the hogweed bonking beetle. (Ah, the uninhibited internet; not something I had learned from my insect guidebook.) The red soldier beetle is apparently the most conspicuously promiscuous insect in these isles. They are even known to fly in copula.

I said above that it was male on female, but I can't actually distinguish the sexes. I seem to remember a report in Nature or Science some time ago about a species of beetle of which two females will pretend to mount as a way of attracting the most aggressive males, one of whom will jealously try to push away what he thinks is a weaker rival and have the damsel for himself. Discovering the ruse, he mates with one or the other of the sneaky gals. Ah, the wonderful stratagems of natural selection.

(My camera is not so good at close-ups. You can click to enlarge the pic.)