What has nibbled it's way through these leaves of broad-leaved dock, or Rumex obtusifolius? A quick clue....this species has featured in a blog from a few weeks ago. Answer next week....
Did anyone get this one? The dock plant has been eaten by the larvae of Gastrophysa viridula, also known as the green dock beetle, which was pictured in a blog from a few weeks ago. These beetles are members of the Family Chrysomelidae, the leaf beetles and are one of the most common leaf beetles you will see throughout the UK.
The beetles breed from March to October and can produce as many as four generations per year. The eggs are laid in clusters on the undersides of the foodplant leaves, with each female laying up to 1000 eggs per year. Clusters of yellow/orange coloured eggs can be seen by searching the undersides of dock leaves throughout the beetle's breeding season. Eggs hatch after only 4-6 days and the dark coloured larvae then feed up on dock leaves until they reach about 8mm in length. Pupation occurs underground, where the larvae metamorphose, the imago (adult) insects emerging after around 7-9 days.
The imago insects are a metallic green in colour and are about 5-6mm in length. When full of eggs (gravid), the females have massively swollen abdomen, pushing the green elytra (wing cases) upwards. This exposes the black exoskeleton beneath.