Overview
Most adult geometrids are nocturnal and rest during the day with their cryptic-coloured wings spread out and closely appressed to the surface. Larentiinae are often diurnal, particularly in subalpine areas. The reduced number of ventral prolegs results in the larvae progressing with a looping motion, hence the name loopers. McGuffin (1988) provides keys to subfamilies.
Description
Small to large; head usually smooth-scaled; ocelli usually absent; chaetosemata present; antennae simple or pectinate; proboscis present, unscaled; maxillary palps very small, 1- or rarely 2-segmented; labial palps usually small, upturned or porrect; epiphysis present; spurs usually 0-2-4; male hind tibiae sometimes modified; wings broad, sometimes reduced in females, fore wing often triangular, discal cell rarely to beyond midlength, often with 1 or 2 areoles; fore wing with Sc close to or partly fused with R
1
, R
4
and R
5
always stalked, M
2
not arising nearer to M
3
than M
1
, CuP absent, 1A+2A sometimes with small basal fork; hind wing with 2 or more frenular bristles in female, humeral angle usually expanded, humeral vein often present from angle of Sc, Sc approximated to, or fused with, Rs near base, or joined to Rs by R
1
, and then divergent, M
2
not arising nearer to M
3
than M
1
or absent, anal area narrow, 1 or 2 anal veins; abdomen often slender; paired tympanal organs present in invaginations of the anterior part of S2, inner side of each tympanal membrane with a thickened border and a sclerotised arm (ansa), with 4 acoustic sense cells. Larva usually long and slender, ventral prolegs sometimes present on segments 3-6, 4-6, 5 and 6 or, more usually, only 6, prolegs on 6 often posterior, anal prolegs massive; crochets biordinal in curved mesoseries, rarely uniordinal; prothorax with 2, rarely 3, L setae; often twig- or leaf-like, rarely in loose shelter, usually feeding fully exposed. Pupa with cremaster well developed, often with hooked setae; without dorsal spines; usually in flimsy cocoon in debris or in soil; not protruded at ecdysis. [McFarland 1988.]