Spruce Budworm Alert
Spruce budworms and relatives are a group of closely related insects in the genus Choristoneura. Most are serious pests of conifers. There are nearly forty Choristoneura species, and even more subspecies, or forms, with a complexity of variation among populations found throughout much of the United States and Canada, and about again this number in Eurasia.
Budworm populations are usually regulated naturally by combinations of several natural factors such as insect parasites, vertebrate and invertebrate predators, and adverse weather conditions. During prolonged outbreaks when stands become heavily defoliated, starvation can be an important mortality factor in regulating populations.This species is a favoured food of the Cape May Warbler, which is therefore closely associated with its host plant, Balsam Fir. This bird, and the Tennessee and Bay-breasted Warblers, which also have a preference for budworm, lay more eggs and are more numerous in years of budworm abundance.
Natural enemies are probably responsible for considerable mortality when budworm populations are low, but seldom have a regulating influence when populations are in epidemic proportions.
Chemical insecticides such as malathion, carbaryl, and acephate can substantially reduce budworm. Microbial insecticides such as the bacterium Bacillus thuringiensis, a naturally occurring, host-specific pathogen that affects only the larvae of lepidopterous insects is environmentally safe to use in sensitive areas such as campgrounds or along rivers or streams where it may not be desirable to use chemical