Brief Summary
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Alsophila pometaria, the fall cankerworm, is a lepidopteran pest of hardwood and shade trees, and is native to North America. The larvae (caterpillars) commonly feed on ash, basswood, beech, black cherry, red maple, sugar maple, red oak, and white oak, but will also eat apple, birch, boxelder, dogwood, elm, hickory, and many other hardwoods. The adults are active in the fall, usually emerging from their pupal phase in October to lay orderly clusters of about 100 eggs lined up in neat rows, which overwinter on the small twigs to which they adhered. This lifecycle differentiates the fall cankerworm from the very similar but less common spring cankerworm, Paleacrita vernata, which overwinters as a pupa and is active as an adult to mate and lay eggs in the spring. Both cankerworms feed on the same trees and have overlapping ranges. Population numbers of fall cankerworm naturally fluctuate and reach populations large abundance every 15-20 years. While outbreaks of cankerworms, which last several years, can defoliate trees, healthy trees usually recover without significant damage even when attacked for two years in a row. In outbreaks cankerworms are seen as a nuisance in public areas when in late summer the larvae (small green caterpillars known as loopers or inchworms) drop from trees on silk webs in large numbers on their way to finding spots to pupate, and then again as the adult moths climb buildings to lay their eggs. While adult male moths are grayish-brown with a wingspan of about three centimeters, female moths are wingless, and look more like a spider than a moth.
(Ascerno and Hanh, 2003; Hoover and Haydt, 2010)
Conservation Status
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No concern; often reaching pest status.
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Cyclicity
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Adults fly after the first fall frosts have occured, peaking in mid October.
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Distribution
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Nova Scotia west to Alberta, south to Colorado and California (McGuffin 1988). In Saskatchewan and Alberta, this species is associated with Manitoba Maple shelter belts in the southern parts of the province. It did not occur historically in the Edmonton region, but is now established here and is often common in October on city Elm trees.
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General Description
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Males have an even brownish grey forewing with jagged white and dark PM and AM lines, occasionally with a visible dark discal spot. The hindwings are light grey, with a dark discal spot and a faint pale PM line. The females are wingless and stout-bodied, looking very unlike a lepidopteran.
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Habitat
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Wooded areas including city parks, ornamental plantations and shelter belts.
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Life Cycle
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The larvae are often a serious pest of many tree species elsewhere, although it rarely reaches densities high enough to do damage in Alberta. The eggs are laid in clusters on tree branches and trunks by the wingless females and hatch the following spring, synchronized with the flush of leaves. There are four larval stages, which are described in detail by McGuffin (1988). Larvae pupate in the soil and delay their emergence until fall, spending about four summer months as a pupa. Females in at least some populations are able to reproduce parthenogenetically (without mating). (McGuffin 1988).
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Trophic Strategy
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Larvae feed on a large variety of deciduous trees and shrubs, especially elm (Ulmus spp.), ash (Fraxinus spp.), and maple (Acer spp.), which are non-native to Alberta but often planted in cities and as shelterbelts.
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Alsophila pometaria
provided by wikipedia EN
Alsophila pometaria, the fall cankerworm, is a moth of the family Geometridae. The species was first described in English by the KJV Bible [Joel 1:4]. It is found in North America from Nova Scotia west to Alberta, south to Colorado and California and zones of Spain
Description
The caterpillars grow to about 25 mm long. In color, they vary from light green to a dark brownish green. Light green caterpillars have white lines running down the body from the head to the tip of the abdomen while the darker caterpillars have a black stripe the length of their back. Larvae have three pairs of legs on their thorax and three pairs of prolegs on their abdomen. The first pair of prolegs is much smaller than the last two pairs. The pupa is wrapped in a silk cocoon and is buried just beneath the surface of the ground.[1]
Adult males have a 25–35 mm wingspan. The forewings are glossy brown and crossed with irregular white bands. The females are brownish gray, wingless, and 10–12 mm long. Eggs are grayish brown with a dot and ring on the top and are less than 1 mm in diameter.[1]
Biology
The larvae feed on a large variety of deciduous trees and shrubs, including Ulmus, Fraxinus and Acer. Other recorded hosts include hackberry, oak, various members of the rose family, walnut and willow.[1] The larvae hatch and are active in the spring. These insects are called fall cankerworms because the females emerge from the soil in November, mate and lay their eggs in clusters on hardwood trees.[2]
There are some natural enemies of this species. Many birds eat the caterpillars. The ground beetle, Calosoma frigidum also feeds on the caterpillars. The wasp, Telenomus alsophilae, parasitizes the eggs.[1]
Economic importance
The larvae, called loopers or inchworms, are considered a serious pest of many tree species because they can cause major defoliation in the new spring growth. If defoliation occurs two years in a row, the tree can die, especially if it has been stressed by drought.[1]
References
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Alsophila pometaria: Brief Summary
provided by wikipedia EN
Alsophila pometaria, the fall cankerworm, is a moth of the family Geometridae. The species was first described in English by the KJV Bible [Joel 1:4]. It is found in North America from Nova Scotia west to Alberta, south to Colorado and California and zones of Spain
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