Arge berberidis (Schrank, 1802)
Common name: Berberis Sawfly.
Family: Argidae.
Length: Around 9.2mm
Adults fly: June to August.
This is a widespread species, found in most countries of Europe, wherever the larvae host plants grow; the host plants belong to the genus Mahonia and Berberis shrubs.
The larvae (resembling a caterpillar, creamy white with black heads, about 18mm in length) are a serious pest to the host shrubs, as they can cause complete defoliation. The adult sawfly lays her eggs well-hidden, between the leaves of the plant, which makes them very difficult to find. When hatched, the larvae will very quickly strip parts of the plant of leaves. Once the larvae have matured fully, they will burrow beneath the soil to pupate, within a silken-spun cocoon during the winter months.
First recoded in Southern Britain as recently as 2002, now it is being found as far north as Yorkshire.