WHAT IS IT?
The spruce budworm, Choristoneura fumiferana(Clem.), is one of the most destructive insects of softwood trees. In Atlantic Canada, it feeds mostly on balsam fir (Abies balsamea L.), but may also attack spruce (Picea spp.), larch (Larix spp.), and hemlock (Tsuga canadensis (L.) Carr.) in years of severe infestation.

WHAT DOES IT LOOK LIKE?
The adult budworm moth is grayish with dark brown and pale markings, and is about 1.5 cm long, with a wingspan of about 2.5–3 cm. Adults mate during the last half of July. They are most active between 7:30 and 11:30 p.m. They can disperse over long distances (>25 km), transported on prevailing wind currents. Under storm conditions, they may be dispersed hundreds of kilometers away from their point of origin. Females lay their eggs on the undersurfaces of needles of the host tree. However, if budworm populations are high, eggs may be laid almost anywhere.

The eggs are laid in masses of 15 to 50 in overlapping rows. In general, female moths deposit an average of ten egg masses, a portion of which are laid near where the female emerges. The remaining eggs are laid after the female has migrated to new sites. After laying the eggs, the female moths die (male moths die after mating). The eggs are light green and about 1 mm long and 0.2 mm wide. They hatch after about 10–14 days. The young larvae crawl into crevices on the twigs and branches, where they spin a small silken shelter, or hibernaculum, in which they overwinter. About the time the buds begin to swell, the larvae emerge from their hibernacula and start feeding, mining the needles and buds.

When fully grown (about June 15–30 in Fredericton, NB), the caterpillar can be found in a thin web on the foliage; it is about 2.5 cm long and pale brown with light spots and a dark (brownblack) head. The caterpillar changes into a brown pupa within the web and, about 10 days later, the moth emerges to mate and lay eggs for the next generation.

Source : http://cfs.nrcan.gc.ca/news/455

For more information

• Canadian Food Inspection Agency

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