|scientific name Choristoneura fumiferana |
common name Eastern spruce budworm
Balsam fir (Abies balsamea) and white spruce (Picea glauca) forests.
Adults first appear in mid June and are present throughout July.
Mature larvae are 20-22 mm long, yellowish brown with black heads. Adults with grey head and thorax, rarely reddish brown in females. Forewing typically gray with suffused, indistinct markings. Males occasionally and females more commonly have reddish brown hue. Hind wing uniformly dark brown or grayish black. Fringe whitish with dark basal line. Wingspan: males 21-26 mm, females 22-30 mm. For more detailed information see Freeman (1967). Color and pattern of the forewing can vary significantly and morphological resemblances among conifer-feeding Choristoneura make it very difficult to distinguish species using external morphological characteristics (Dang 1985). To identify species, other characters should be considered such as genitalia (Dang 1985, Dang 1992), mitochondrial DNA (Sperling & Hickey 1995) or behavioural characteristics such as host plant preference, larval diapause or pheromone attraction.
Female adult lays up to 200 eggs during a two week period in July. Eggs are laid in masses of 15-50 that resemble overlapping green scales along undersides of needles. Eggs hatch in 10 days and larvae spin silken hibernation shelters under bark scales, lichens or in old staminate flower cups to overwinter (Cerezke 1991, EPPO 2004). Larvae emerge from hibernation the following year from late April to mid May just before vegetative buds begin expanding. They mine into old needles, unopened buds, or feed on staminate flowers. Eventually they move to opening buds where they produce a silken cover to feed under. Larvae spin loose webs among the needles which they use to move to new foliage as the shoots expand. Larvae drop to lower branches or remain in feeding webs to pupate after the sixth larval instar. Adults emerge approximately 10 days after pupation. One generation per year (EPPO 2004).
Not of concern.
Principal hosts are balsam fir and white spruce but will also feed on black (Picea mariana), red (Picea rubens), Norway (Picea abies), Engelmann (Picea engelmannii), and Colorado (Picea pungens) spruce, as well as hemlock (Tsuga heterophylla), larch (Larix laricina, Larix occidentalis) and subalpine fir (Abies lasiocarpa) (Harvey 1984, Cerezke 1991).
Mainly associated with boreal, Great Lakes-St. Lawrence and Acadian forest regions where balsam fir and white spruce are found. Ranges from the Atlantic provinces to the Rocky Mountains in Alberta and northward to the Arctic circle in the Mackenzie River valley and the Yukon (Harvey 1984).
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