Alder Sawfly

The Alder Sawfly has a black head and abdomen and dark orange-red thorax.

They are usually found in areas with Alder trees.

There are two generations a year. The adults of the first generation appear in May and June and the second generation appear in July and August.

The larvae are up to 2 cm long and covered in a white powdery substance. They have evolved a cunning strategy to avoid being eaten, by disguising themselves as bird droppings. The white powdery substance is easily rubbed off and in the final instar, when feeding is finished, the white powder is lost and the larva adopts a pale green appearance. The larvae feed on Common Alder.

Until the late 1990s the Alder Sawfly was thought to be extinct in Britain. It has since been found in southern England and has been slowly spreading northwards.