• Environment Canada
  Canadian Forestry Service
  

The spruce budworm, Choristoneura fumiferana (Clemens), is one of the most destructive insects of coniferous species, but in eastern Canada it is primarily a pest on balsam fir.

During outbreaks the larvae may destroy most or all the new foliage and sometimes all the buds and shoots. Trees will put out new growth the next year and will recover unless the attack remains severe for 3 or more years. After 3 years of severe defoliation, many balsam fir trees may have dead tops, be stunted, or have died. Small trees are seldom killed unless growing under larger trees. In areas of moderate to severe infestation, however, trees of the size used for Christmas trees are likely to sustain sufficient damage to cause downgrading or rejection. Trees damaged by budworm or other insects should not be cut because if they are left for a few years they will often recover and become suitable for Christmas trees.