Our common green shield bug, Palomena prasina, is widespread in the UK. It is seldom, if ever, troublesome and is a bug you can enjoy sharing your garden with.
The bugs show an incredible diversity in their appearance as they develop: from little tiny round green babies with black dots, they grow bigger and bigger until finally acquiring their characteristic shield shape.
Shield bugs like nothing better than to lounge in the sun, occasionally sucking a bit of sap from a wide variety of plants, but without causing damage. Hazelnut growers do regard them as a pest as the hazel is their favourite food. And if too many shield bugs suck the sap of the hazel trees, the nuts tend to drop early without forming properly.
There is another similar shield bug that is common in continental Europe and has also been seen regularly in the south of the UK: the southern green shield bug, Nezara viridula. This shield bug is a serious pest and its spread in the UK is being monitored.