Spruce Budworm

Spruce Budworm occurs throughout Colorado and is regarded by the US Forest Service as the most widely distributed and destructive defoliator of coniferous trees in the west.  Spruce Budworms feed on foliage, flowers, and developing cones resulting in cone destruction.  There are many different species of budworm, though no specific outbreak pattern has been detected since they began in 1914.  In one particular Rocky Mountain epidemic lastly nearly 30 years, more than 6 million acres were destroyed.  Obvious insect damage typically begins in the tree crown as brown, dead foliage.  Successive years of defoliation will likely kill a once-healthy tree.

Adult moths of both sexes are similar in appearance, although the females are a bit more robust than males – both are capable of flight. The gray or orange-brown forewings are streaked, and each usually has a white dot on the wing.  Egg masses laid on the underside of needles are oval, light green, and overlap like shingles.  Overwintered larvae emerge in spring before buds emerge.  Adults actively consume foliage from June to August.  Adults lay eggs on the underside of needles.  Beginning in May, look for frass (fecies) and silk webs on buds and needles.

In addition to chemical insecticides, a microbial insecticide can be used to control some Spruce Budworm populations.  These have the added advantage of being a host-specific pathogen and is environmentally safe to use in very sensitive areas. Walker Tree Care has a plant healthcare department that is trained and equipped to deal with infestation and prevention of all species of Spruce Budworm.