Eastern blackheaded budworm
Damage, symptoms and biology
The eastern blackheaded budworm affects the upper part of the crowns of trees. The larvae are responsible for the partial or total destruction of current-year foliage and, in cases of severe infestations on fir, of the previous years’ foliage. Major outbreaks can result in significant growth loss and, if defoliation is severe, in crown mortality.
Mature larva is up to 16 mm long. The head is black with a black thoracic shield. The body is green to yellowish green, lacking distinct markings.
This species overwinters in the egg stage. Eggs hatch from May to early June. The larvae feed on the new foliage, webbing needles together to form protected feeding shelters. Although they usually confine their feeding to current growth, during outbreaks they will feed on old foliage after the new foliage is consumed. Larvae feed until late July to early August, then pupate on the twigs within a web made of dead needles. Adults emerge 2 to 3 weeks later and lay eggs singly on the underside of needles.
Newly hatched larvae burrow into the opening buds. They tie several needles together with silk and feed inside these shelters. In June and July, when large numbers of larvae are present, it is possible to observe small green caterpillars with brown or black heads suspended by silk threads looking for a new source of food.
Later in the season, small brown pupae with greenish wings are attached to the ends of twigs or dead needles. In August and September, small grey-brown moths, some with brightly coloured markings, fly around the defoliated crowns of the trees. The eggs are laid singly on the undersides of needles. The winter is spent in the egg stage.
Life cycle (East of the Rockies)
Damage caused by eastern blackheaded budworm, a species native to North America, has sometimes been confused with that of the spruce budworm. The species was first identified with certainty during an infestation in the Maritime provinces between 1929 and 1934.
A series of infestations throughout all of eastern Canada, except Ontario, was also reported between 1945 and 1950. These infestations were particularly severe in the central and eastern Gaspé Peninsula in Quebec. Small infestations were reported in northeastern British Columbia in 1994 and 1996. In Newfoundland, large populations of this insect continue to be frequently reported in fir forests.
Canadian Forest Service Publications
Diet and feeding behaviour
: Feeds on the leaves of plants.
- Webworm: Spins a silk shelter in which to hide or feed.
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