Threelined larch sawfly

French common name: Tenthrède trilignée
Scientific name: Anoplonyx luteipes (Cresson)
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Tenthredinidae

Distribution

Canada

The threelined larch sawfly occurs throughout northeastern British Columbia; it also occurs east to Newfoundland, north to the Yukon and south to Maine and Minnesota.

Damage, symptoms and biology

The threelined larch sawfly is a common solitary defoliator. Damaging outbreaks have not been recorded in British Columbia.

Mature larva up to 15 mm long. Head, yellowish brown with black eyes. The larvae are tapered caudad with the thorax larger than the abdomen. Body, green marked with a faint middorsal pinstripe and well-defined olive green addorsal, supraspiracular, and epipleural stripes.

This species overwinters as a prepupal larva in a cocoon buried in the soil. Adults emerge in late May and the females lay eggs, usually singly, into slits cut into the needles. Larvae are present from mid-June to July. Mature larvae drop to the ground and spin cocoons in late July.