Large aspen tortrix
Damage, symptoms and biology
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.
Life cycle (East of the Rockies)
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 two to three 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 three major outbreaks since 1938. In the three 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 caterpillars.
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 one 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.
Canadian Forest Service Publications
Diet and feeding behaviour
: 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.
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