Two species of green shield bug now occur in Britain. The common green shield bug is native to Britain, and of widespread occurrence. The southern green shield bug is a recent arrival from elsewhere in Europe that became established in the London area in 2003.
Common green shield bug and southern green shield bug
Palomena prasina and Nezara viridula
Common green shield bug: various plants. Southern green shield bug: runner bean, tomato and raspberry; also found on the seed heads of ornamental plants, including Caryopteris, Hibiscus, Agapanthus and Verbena
Main symptoms No damage is caused by the common green shield bug. The southern green shield bug may cause distorted bean pods and damaged fruits
Most active April to October (LINK)