The second instar nymph gradually loses the black shoulder mantle, replacing it with green. This bright green is stippled on the edges with black dots in spring and summer, but changes to green-bronze in autumn. Both the nymphs and the adults are capable of overwintering and most will turn brown just before that. After hibernation it will take them about a week or two to turn completely green.
The name shield bug is due to the shield-like shape of the insect as seen from above. This shape is more rounded in the nymph than in the adult.
Although often mistaken for beetles, shield bugs belong to a different group of insects, the Hemiptera or true bugs. True bugs have mouthparts that are specialised for piercing and sucking: most feed on plant juices though some are predators.
It is sometimes called a green stink bug as it produces a pungent odour from special glands if handled or disturbed.
