Willow sawfly

Willow sawfly (Nematus pavidus). Adult sawflies are 5 to 7.5 mm long, copper-colored insects with two pairs of wings.
The female uses her “ovipositor” (a saw-like device from which the common name “sawfly” is derived) to pierce a leaf and lay 50 to 80 soft yellow eggs on it. From the eggs hatch small, bright green larvae with large black heads. These grow into fresh green/yellow larvae with distinctive stripes. The larvae from the eggs look like caterpillars but are not. Larvae of the willow sawfly have six pairs of abdominal legs, while caterpillars have only 4 or 5 pairs. The larva has a ridged body and grows to about 20 mm in size.
The larvae feed on leaves and then enter the soil to pupate, from which the adult sawflies emerge. Two or three generations may be produced each year.
Sawflies sometimes become a pest and can then completely defoliate a tree.
Sawflies are most common on willow bushes and trees and sometimes on European aspens. The larvae are active during the summer months.
Willow sawfly larvae are controlled with roundworms, the larvae’s natural enemy.