The large aspen tortrix is one of the main insects associated with the
trembling aspen. This species occurs throughout the geographic range of
the trembling aspen, its preferred host. The population of this boreal
pest species periodically swells and remains at a high level for 2 to 3
years, then suddenly crashes. In Eastern Canada, Ontario is the region
most affected by the large aspen tortrix, followed by Quebec, where
there have been 3 major outbreaks since 1938. In the 3 Prairie provinces
and southern Northwest Territories, outbreaks are known to have
occurred in virtually all areas where trembling aspen grows. Sudden
outbreaks of the insect occur over hundreds of square kilometres of
aspen forests, often in association with infestations of forest tent
What's the Problem?
The defoliation caused by the large aspen tortrix does not affect tree survival since it occurs early enough in the summer season to allow the trees to produce new foliage.
The signs that can be used to identify the insect on trees are as follows:
Delayed budbreak in the spring;
Presence of deformed leaves, which are rolled up into a cone or attached together by silk threads, which contain caterpillars or frass;
Thin crowns, which may sometimes be completely defoliated
What Can I Do?
Chemical control is not recommended, primarily because of the effective action of the many parasitoids associated with the large aspen tortrix. On ornamental trees, however, control can be achieved by placing a sticky strip around the trunk about 1 metre above the ground to intercept the larvae as they make their way toward the buds in May or toward their overwintering sites in August.
Additional Information Diet & Feeding behaviour
Phyllophagous: Feeds on the leaves of plants.
Leafroller: Hides and feeds inside a leaf or the tip of a leaf that it has rolled up into a cigar-shaped tube.