fan-foot moths

Zanclognatha is a genus of litter moths known as fan-foot moths. It occurs in Europe, Asia, and North America. In the United States it occurs east of the Great Plains, in the Pacific Northwest, and in Colorado and New Mexico. There are just a handful of records in the U.S. outside of these areas.

There are currently 25 generally recognized and described Zanclognatha species worldwide, 12 species in North America north of Mexico, and at least 10 species in Minnesota. The number of species will almost certainly change in the future. At least two species are expected to be split, some species have yet to be described, and some described species are not widely recognized. iNaturalist currently (2023) lists 39 species.

The fan-foot larvae feed on dead leaves on the forest floor. Partially grown larvae overwinter. There are two generations per year in the south, one generation per year in the north. Adults are found from May to September in wooded areas on or near the ground.

Fan-foot moths are small to medium-sized, litter moths. Adults are challenging to identify to the species level, both because they are difficult to photograph in low light among dead leaves on the ground, and because the wing patterns are not always useful in separating them. They are best identified when in the larval stage.

Fan-foot moths are delta-shaped, slender, and dull colored. The head is prominent. The finger-like sensory mouthparts (labial palps) are long, turned upward, and very prominent. The second segment is blade-like and reaches beyond the top of the head (vertex). The third segment is also blade-like and is more than half as long as the second. On the female, the antennae are lightly bristled, with a single short bristle on each side. On the male, they are heavily bristled, the bristles being longer than the segment to which they are attached. The male antenna also has a thickened section, described as a “knot”, at about one third of its length.

The wings are broad, thin, and uniformly colored, the color ranging from pale to dark. They are held flat when at rest. The forewing is triangular.

On the male, the front legs are highly modified. The first segment (coxa) is long and slender and has an expansible tuft. The third segment (femur) is slender and has a fan-like tuft at the tip. The fourth segment (tibia) has a very long, hollowed out process at the end that encloses a large expansible tuft. On the last part of the leg (tarsus), corresponding to the foot, the first segment is massive and often hollowed out. On the female the front legs are not modified like the males.

4, 29, 30, 71, 75, 82, 83.

The genus Zanclognatha was first described in 1857. In 1989 it was moved to the Eurasian species Polypogon. It was separated from Polypogon in 1991 but rejoined with it in 1996. Two more recent publications, The Lepidoptera of Europe: A Distributional Checklist by Nowacki & Fibiger (1998) and Taxonomic notes on North American Noctuidae 2: The Polypogon group of genera by Lafontaine and Troubridge (2005), recommend retaining Zanclognatha as a separate genus.

Zanclognatha sp. litter moth

Zanclognatha sp., litter moth, photo taken June 12, 2021 at Barnes Prairie hedgerow, Racine Co., WI.

Location: Barnes Prairie hedgerow, Racine Co., WI

Zanclognatha sp., litter moth, photo taken June 12, 2021 at Barnes Prairie hedgerow, Racine Co., WI.