Green Dock Beetles- the full life cycle!

Wonderful iridescent green dock beetles (Gastrophysa viridula) busy making friends, and more dock beetles,in the water meadows below the wood in mid-June. A multilayer composed of chitin layers alternated with layers which also contain melanin is responsible for the green colouration (this phenomenon is known as structural colour).

Lots of images of beetles, larvae and eggs on NatureSpot. The eggs are bright yellow and the ones we found near the beetles look right. Their larvae make lacework out of docks as shown in the picture below, taken by the Thames last month.

Wikipedia is more forthcoming than usual on this species. It says that The green dock beetle’s breeding season is from March to October. There are 2 to 4 broods per year, with the last brood hibernating as an adult. The female lays over 1,000 eggs, laying them in clusters of 20 to 45 on the underside of the food plant’s leaves. The eggs are oval in shape, and are cream to yellow, turning orange prior to hatching. After about 3 to 6 days, the larva hatches from the egg. It varies in color from greenish gray to dark brown. Its body is segmented, and will reach a length of 8 mm. Young larvae will drop to the ground if disturbed while feeding, while older larvae secrete a substance which repels competitors from eating the food plant leaves. After three instars, the larva pupates in a burrow about 2 cm underground. The adult emerges 6 to 9 days later.