linden looper

Linden looper is a medium-sized, late season, typical geometer moth. It occurs in the United States from Maine to northern Georgia, west to Utah and Texas, and in southern Canada from Quebec to Alberta. Since 1994 it has almost disappeared from a large part of New England, and that area is thought to be increasing. It is common in Minnesota.

Adult males fly from late August to early December in the south, in October and November in Minnesota. Adult females are almost wingless and do not fly. Caterpillars feed on the leaves of many shrubs and deciduous trees, including American hornbeam, apple, ash, birch, beech, cherry, elm, hazel, maple, oak, poplar, serviceberry, willow, and as the common name suggests, on basswood. They can cause defoliation when they occur in large numbers.

Adult males have a 1¼″ to 1⅝″ (32 to 42 mm) wingspan. The forewing length is ⅝″ to 1″ (17 to 25 mm).

The top of the head is yellowish-brown to pale brown. The antennae have 37 to 41 segments. Each segment has two pairs of short, squat projections, one pair at the base and another in the middle. Each projection has numerous, long, stiff hairs (setae). The eyes are large, round, and hairless.

The thorax and abdomen are slender.

The forewings are large, broad, almost translucent, and light brown, with dark markings. They are highly variable in both color and markings, but they follow a general pattern. The base color may be pale brown, yellowish-brown, pale salmon-brown, or brown. The antemedial (AM) and postmedial (PM) lines are dark and wavy. They may be thin and well defined, broad and diffuse, or somewhere in between. They may be very dark and distinct or only slightly darker than the background. On some individuals the AM line is not discernible. The discal spot is dark. The wings are peppered with dark scales. The peppering may be heavy, light, or barely discernible. The wings on the female are reduced to minute pads about 1⁄64″ (0.5 mm) in length.

The hindwings are grayish-white and unmarked except for a small discal spot. They are usually peppered with widely spaced grayish-brown scales.

The legs are brown. There are two pairs of spurs on the fourth segment (tibia) of the hind legs, a single pair of spurs at the tip of the tibia of the middle legs, and no spurs on the tibia of the front legs.

The caterpillar is up to 13⁄16″ (3 cm) long and is easily identified. It is brown above with up to ten dark pinstripes. On each side there is a broad, bright yellow stripe through the breathing pores (spiracles). Each spiracle is thinly ringed with black. The head on most individuals is orangish-brown.

Wingspan: 1¼″ to 1⅝″ (32 to 42 mm)

One generation per year: October and November

Males rest with their wings held flat.

Eggs overwinter in crevices in tree bark and hatch in the spring.

Leaves of many shrubs and deciduous trees, including American hornbeam, apple, ash, birch, beech, cherry, elm, hazel, maple, oak, poplar, serviceberry, willow, and basswood

Flower nectar

Sources

4, 7, 21, 24, 27, 29, 30, 75, 82, 83.

Common

Until recently, some taxonomists placed the genus Erannis in the tribe Erannini, while other taxonomists placed it in the tribe Bistonini. The Annotated taxonomic checklist of the Lepidoptera of North America published in 2016 listed the genus in Bistonini. The revision to that checklist was published in 2023, and it lists Erannis in the very broadly circumscribed tribe Boarmiini.

linden looper caterpillar

Crawling on allium stems

Erannis tiliaria - Linden Looper Moth
Andy Reago & Chrissy McClarren

Linden Looper (Erannis tiliaria)
ALForestryCommission

Linden Looper Moth (Geometridae: Erannis tiliaria) Caterpillar
Carl Barrentine

Linden Looper Moth Caterpillar (Geometridae: Erannis tiliaria) Close-up
Carl Barrentine

Stenson
6/1/2024

Location: Bloomington, MN

Crawling on allium stems

Alfredo Colon
6/1/2021

Location: Woodbury, MN