Spruce bud moth

Larva, showing damage inside a spruce shoot, and silk envelope Thérèse Arcand

French common name: Tordeuse de l'épinette
Scientific name: Zeiraphera canadensis Mutuura and Freeman
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Tortricidae
Partial list of synonyms:
- Zeiraphera ratzeburgiana Ratzeburg

Distribution

Canada

Damage, symptoms and biology

Scouting for the spruce budmoth can be done by observing two different signs:

the prolonged presence of the bud cap, held by silk threads at the tip of the annual shoot;
the presence of multiple leaders and branches with many branchlets in the upper crown.

Needles chewed along their margins, or cut off at the base, gradually take on a reddish colour. Although the caterpillars primarily attack apical shoots without any serious consequences during their early development, older caterpillars cause more damage since they are especially fond of the tender bark of twigs, and this leads to shoot breakage during rainfall or heavy winds.

Other information

A native species in North America, the spruce bud moth was first reported in 1938, in Eastern Canada. Associated with the spruce budworm during the drastic outbreak of 1939 to 1958, the spruce bud moth’s presence is very noticeable. The damage it causes is often confused with that wreaked by the spruce budworm. However, Zeiraphera canadensis differs from the spruce budworm in that it prefers to feed on open-growing spruce rather than spruce in forests.