This large bug has a flattened, shield-shaped body and measures between 10 and 15 millimetres. It is bright green in spring and summer, becoming dark bronze-green in autumn, just prior to hibernation. Delicate flecks of black on its body look like small puncture marks.
The green shieldbug can be found at the edges of woodland and in hedgerows, parks and gardens throughout most of Europe.
This species passes through five nymphal stages, moulting between each one. At each stage it has a different colour, and short wings appear in the final stage. The adult stage is reached in September, and the bug hibernates in November. The shieldbug has specialised sucking mouthparts, which are used to obtain plant sap. It feeds on a wide range of trees, shrubs and tall herbaceous plants.