|scientific name Tetracis |
Forests and woodlands.
Adults fly in spring; late (late May-June) in Alberta.
The genus Tetracis belongs in the Lepidoptera family Geometridae, subfamily Ennominae, Tribe Ourapterygini. It is a small genus containing two North American species, cachexiata and crocallata, both described by Guenee in 1857. They are medium-sized (approx. 3.5-4 cm wingspan) creamy white, pale yellow or yellow-brown moths with angular, pointed forewings crossed at an angle by a straight line from the apex to midway on the lower margin. This line gives them their common name of Yellow (crocallata) and White Slant-line (cachexiata). Similar Alberta species of geometrid moths have the forewing line bent abruptly basad before reaching the apex (Prochorodes), or meeting the costa well short of the apex (Euchlaena species).
The larvae are described and illustrated in color in Wagner et al, 2001.
Tetracis are single brooded, and overwinter in the pupal stage. The larvae are solitary defoliators of woody trees and shrubs.
Relatively common, widespread species; no concerns.
Tetracis larvae utilize a wide variety of deciduous (crocallata) or deciduous and evergreen (cachexiata) trees and shrubs.
Cachexiata occurs from coast to coast across southern Canada and crocallata occurs west to Alberta; both range southward in the forests of eastern North America. Both species occur in Alberta, with cachexiata found mainly in the drier grasslands region of the province, and crocallata in the cooler parklands and southern boreal forest regions.
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