Spruce Budworm

Order:  Lepidoptera

Family:    Tortricidae

Latin Name:     Choristoneura fumiferana (Clemens)

Common Names:    Spruce Budworm, Eastern Spruce Budworm

The spruce budworm has caused more damage to Nova Scotian softwood forests than any other insect. Overmature balsam fir is the preferred host and acts as a flash point for rapid population buildup. Populations tend to increase steadily and spread to younger trees. Feeding takes place on the top third of the tree on new shoots. High populations will result in repeated loss of all new foliage which will kill the trees within 3 - 4 years.


Life History
In late August or September, the eggs hatch, the larvae molt, and overwinter in the second instar. In late April or early May, the larvae (3 mm long) emerge from their hibernacula and begin to feed, mining the needles and buds. A week later they move to feed on the closed buds and any developing shoots. The larvae are fully grown within five weeks. They have black heads and a dark brown body, 18 - 24 mm long. They pupate on the foliage and the adult moths emerge in July to lay eggs which hatch in 2 - 3 weeks. The adults are dull grey with a wingspan of 20 mm.


Damage Symptoms
Defoliated trees over large areas with red foliage; particularly the new foliage on the upper third of the tree.


Control Options
Harvest stands of overmature fir and spruce to remove potential population build up sites. Biological control products are recommended for large forested areas. These will not interfere with naturally occurring parasites and diseases that help control budworm populations.

For ornamental fir and spruces, both biological or contact insecticide can be used. When using a biological insecticide such as Btk, the product should be applied while the larvae are in the open and feeding. Contact insecticides should be applied while the larvae are exposed and not hidden under the bud caps.

CAUTION: Read and follow the instructions on the label when using any control agent. Proper application and use of recommended personal protective equipment are essential for the safe use and effectiveness of any pesticide.

DISCLAIMER: Control options are suggestions only. Actions taken for pest control are the sole responsibility of the applicator in full compliance with any Federal, Provincial or Municipal Acts, Regulations or Bylaws.