Large aspen tortrix

Large aspen tortrix - Mature larva (length: 15-25 mm)
  • Latin name: Choristoneura conflictana (Walker)
  • French name: Tordeuse du tremble
  • Order: Lepidoptera
  • Family: Tortricidae
Description

Distribution

Canada

Micro-habitat(s)

Leaf

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

  1. delayed budbreak in the spring;
  2. presence of deformed leaves, which are rolled up into a cone or attached together by silk threads, which contain caterpillars or frass;
  3. thin crowns, which may sometimes be completely defoliated.

Life cycle (East of the Rockies)

Life cycle (East of the Rockies)
Stage/Month J F M A M J J A S O N D
Larva
 
 
Egg
 
Adult
 
Pupa
 

Other information

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

Large aspen tortrix

Diet and 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.
Information on host(s)

Main host(s)

Balsam poplar, trembling aspen

Photos
  • Large aspen tortrix Adult at rest (winspan: 25-35 mm)
  • Large aspen tortrix Mature larva (length: 15-25 mm)
  • Large aspen tortrix Pupa in its natural environment (length: 9-17 mm)
  • Large aspen tortrix Rolled leaf of trembling aspen
  • Large aspen tortrix Mass of partially hatched eggs on a trembling aspen leaf
  • Large aspen tortrix Closer view of several moderately defoliated trembling aspens
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