Large aspen tortrix

The Large aspen tortrix (Choristoneura conflictana) is a moth belonging to the family Tortricidae. It is widely recognized as a significant forest pest, particularly in the northern regions, where it frequently causes widespread defoliation of aspen stands during massive outbreaks.

While the primary host species is trembling aspen, this insect is known to infest other broad-leaved trees such as birch and willow. The ability to switch between hosts allows the pest to sustain its population levels even when the availability of its preferred host fluctuates across a landscape.

The life cycle of the species is univoltine, meaning it completes one generation per year. Larvae overwinter in the second instar inside silken hibernacula tucked into bark crevices. In the spring, they emerge to feed on developing buds and foliage, progressing through several larval instars before pupating in rolled leaves.

The damage caused by the larvae is characterized by leaf skeletonizing and webbing. By rolling leaves into protective structures, the larvae shield themselves while consuming leaf tissues. Significant infestations can strip entire stands of their foliage, leading to reduced tree vigor, crown dieback, and potential mortality if outbreaks persist.

Management strategies focus on integrated pest management (IPM) practices. Biological control, particularly the application of Bacillus thuringiensis, is the preferred method during larval outbreaks. Monitoring programs using pheromone traps are essential for predicting population spikes and timing intervention efforts effectively.