Green Dock Leaf Beetles

I found scores of these green dock leaf beetles Gastrophysa viridula mating on dock leaves in the pastures beside the River Towy near Carmarthen earlier this week. The larvae chew holes on the dock leaves then pupate in the soil. In a good year they can produce three generations.

The beetles have beautifully iridescent exoskeletons which change from metallic green to bronze depending on the angle of the light. A single female can lay up to 1000 eggs. For the males, finding a female to mate with is highly competitive. In the top picture you can see two males confronting one another over a female.....

... and in this picture you can see a startling case of coitus interruptus, where a mating male - still coupled to the female - has been dragged off her by a rival. I thought this sort of thing only went on in the Bigg Market in Newcastle on a Friday night.....