Do epidemics always begin in western Quebec and end in the east?
Current hypotheses tend more to view this phenomenon in terms of a rising and subsiding tide. As the spruce budworm is always present on the land of Quebec, the outbreak of an epidemic is instead the result of a combination of factors favourable to this insect, such as an appropriate climate, good fertility among females, and the relative absence of natural enemies. After several years (generally 8 to 10, depending on the region), conditions become less favourable, and predators can regain control, thus bringing down spruce budworm populations. In short, the epidemic cycle appears to be governed by not one but several factors.
