Green Dock Beetle Gastrophysa viridula
Many smaller Leaf Beetles are shiny and either blueish, blackish or greenish. But depending on the light they reflect all kinds of colours. Many of these species can be best identified by examining the foodplant. In this case the animal was found on a Rumex species (Dock). And as the larvae fully depend on Dock to develop, this certainly is the Green Dock Beetle, also known as the Green Dock Leaf Beetle or the Green Sorrel Beetle. The basic colour is green and while females are up to 7 mm in length, males measure 3 to 4 mm only. There is a metallic shimmer not only on the shields, but on the legs as well.
The larvae are brownish or blackish with sparse but tough hairs. They are a crossing between caterpillars and worms, like the larvae of most smaller leaf beetles. They may measure up to 8 mm. As there are 3 to 4 overlapping breeds a year, it is very common to see eggs, larvae and adults of this beetle together on one and the same plant. The eggs are laid in groups of some 40 to 50 eggs on the underside of a leaf. They hatch in less than one week. The larvae may be greenish brown when young, but they get darker later. There are only three instars. Full grown larvae pupate underground at a depth of some 2 cm. Adult beetles are seen from May to October.
The Green Dock Beetle is a common species all over Europe, eastwards found in the Caucasus and Western Siberia.