Geometridae

55. Geometridae – inchworm moths; loopers

Primarily medium-sized (but ranging from 10 to 60 mm wingspan) moths with relatively slender bodies and broad, butterfly-like wings. The group is united by the unique structure of the abdominal tympanal organs and by the form of the larvae, which have only two pairs of abdominal prolegs, with the exception of a few species that lack this character. Th e moths in this family are commonly called loopers or inchworms for their larval crawling habit. Although some adults are brightly or boldly colored, most exhibit subtle patterns with browns and grays, often cryptically colored to match bark or leaves. Many geometrids rest with the fore- and hindwing to the side and appressed to the resting surface, exhibiting a continuation of pattern and color between fore- and hindwings. The larvae of most species feed on trees and shrubs, both deciduous and coniferous. Given their diversity, abundance, degree of host specialization, and broad distribution, members of the Geometridae represent a significant component of most forest insect communities. The family Geometridae is one of the three largest lepidopteran families, encompassing about 21 000 described species, primarily in the tropics. About 1400 species of Geometridae occur in North America, 293 of which are reported from AB. Relationships at the subfamily level have been reassessed recently; Young (2006) showed that the subfamily Larentiinae is almost certainly basal within the Geometridae and that Ennominae as currently defined is not monophyletic (see also Abraham et al. 2001). The subfamily Sterrhinae is placed as the second-most basal group. Th e order in which the Geometridae subfamilies are presented here follows these new findings.