Greenheaded spruce sawfly

Lateral view of mature larva, on Engelmann spruce

French common name: Tenthrède à tête verte de l'épinette
Scientific name: Pikonema dimmockii Cresson
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Tenthredinidae

Distribution

Canada

Damage, symptoms and biology

The greenheaded spruce sawfly is common and is frequently found together with the yellowheaded sawfly but is considerably less damaging.

Mature larva to 20 mm long. Head, green marked with black stripes along the vertex and sides. Body, green with prominent white addorsal and spiracular stripes.

This species overwinters as a prepupal larva in a cocoon buried in the duff or subsoil. Adults emerge in May and lay their eggs on the new flush. Larvae initially feed on the current year's needles then move onto the old needles. Larvae are active from mid-June to July when they drop to the ground and spin overwintering cocoons.