Common Green Shield Bug - Palomena prasina

I came across another shield bug today when I found this common green shield bug sitting on the the leaves of a phlox plant in the garden this afternoon. This is a large shield bug that is common throughout Britain, but less so in Scotland.

There is one generation a year, with eggs laid in June and the larvae going through a series of instars, all slightly different in appearance. The barrel-shaped eggs are laid on the undersides of leaves. Both nymphs and adults feed on plant sap. The photograph below is of a 5th instar that I found in the garden in mid August, very near to the place I found the adult today. This developmental process from egg to adult through the series on instars is known as hemimetabolous development (1). Each of the instars resemble the adults but are wingless.

Each instar stage has different colouration, and the final adult stage is reached in September. The adults then hibernate over winter and reemerge to breed in the late spring. The anatomy of the shield bug mean that mating has to take place back to back as stiff body prevent mating in any other way.

1: Martin, J. Hemiptera...It's a Bug's Life. http://www.nhm.ac.uk/resources-rx/files/26feat_its_a_bugs_life-3013.pdf