Eastern spruce budworm populations can experience significant oscillations, with large outbreaks sometimes resulting in wide scale tree mortality.

As a result, the eastern spruce budworm is considered one of the most destructive forest pests in North America, and various methods of control are utilized.

Clemens originally named the eastern spruce budworm, C. fumiferana, in 1865, which was recognized as a Nearctic representative of the genus Choristoneura.

[4] Field collections of late instar larvae of Choristoneura populations were taken from a range of localities in a wide arc, from the Atlantic seaboard along the edge of the Laurentian Shield to the Mackenzie River area near the Arctic Ocean.

[5] The two-year-cycle budworm C. biennis occurs only in the subalpine forest region,[6][7] with alpine fir and interior spruce as hosts.

[19][20][21] The dietary preference for balsam fir over white spruce has the potential to alter the structure and composition of spruce-fir forests.

Similarly, the next-generation stand of trees are influenced by the late instar larvae that disperse to the understory of the forest and feed on the regeneration of plants.

When food becomes depleted, the larvae feed on old foliage, which will result in slowed development and reduced fecundity in the female moths.

One study found possible negative consequences of ingesting balsam fir as it may release juices that adversely affect the midgut microbiota.

[29] As with other species in the genus Choristoneura, spruce budworm females produce sex pheromones to attract males as potential mates and enhance their base level of sexual activity.

[33] Upon copulation, males transfer a spermatophore containing its ejaculate and additional nutrients to the female, which functions as a nuptial gift.

Males that feed on young foliage have been found to grow bigger, produce larger spermatophores, and often have more success in attracting a female.

[38] The second-instar larvae emerge in early May and disperse to feed on seed, pollen cones, flower bracts, and needles at host trees, preferably the balsam fir.

Late instar larvae have dark brown heads and prothoracic shields and are 3 centimeters long when fully developed.

In northern Minnesota, spruce budworm moths emigrate to the east lakeshore of Lake Superior in Ontario, Canada, because of seasonal changes.

[28] In spruce-fir forests throughout Maine, the late-instar spruce budworm larvae is preyed on by eumenid wasps such as the A. adiabatus, and E. leucomelas.

When the weather is warm in late fall and early spring, the budworm may metabolize at a higher rate, which depletes its finite food resources while in the hibernaculae.

Two-year life cycles typically occur in regions with low average daily temperatures and short, frost-free seasons.

According to one common theory (the double equilibrium hypothesis), popularized in the 1970s, periodic outbreaks of the spruce budworm are a part of the natural cycle of events associated with the maturing of balsam fir.

[44] The catastrophe theory of budworm outbreaks holds that particularly major infestations occur every 40–60 years, as the result of a cusp-catastrophe event, whereby populations jump suddenly from endemic to epidemic levels.

[23] Although the white spruce is more resistant to budworm attack than balsam fir, heavy defoliation can occur during severe outbreaks, which results in reduction of radial growth.

In lesser outbreaks, radial growth is moderately reduced, which often makes it difficult to distinguish if it is caused by random or weather-related fluctuations.

[49][50] Massive outbreaks of spruce budworm occur irregularly throughout the range, but populations of this insect can remain at an endemic level for long periods.

[25] Turner found evidence of a budworm attack in the Lake Nipigon region of Ontario occurring with the 1704 outbreak in Quebec's Laurentide Park.

[60] However, in the Lac Seul infestation in northwestern Ontario, apparent radial growth suppression in white spruce first occurred in the 2nd and 3rd years of severe defoliation.

Management occurs through some manipulation of the environment, which is determined through cultural practice, or by the introduction of a regulatory agent such as a predator or an insecticide.

Although a scattering of dead trees occurred throughout the region, in no case did mortality destroy a major operating unit or disrupt a long-term management plan.

A 1989 study found that woodland birds cannot effectively control the damage caused by budworms during outbreaks because their food requirements are exceeded.

[9] Inundated releases of Trichogramma minutum Ril., a species of parasitic wasp, have also been investigated for use as a biological control of Choristoneura fumiferana.

Temperature and host egg differences also influenced the biological characteristics of reared parasites, which could possibly affect the success of field releases.