Montana Field Guide

The Mythimna unipuncta wingspan is 35 - 47 mm. The forewing is tan, and often tinged with orange and lightly speckled with black. The postmedian line is a series of small widely-spaced black dots. The discal spot is white. A black-shaded line slants inward from the apex. The hindwing is grayish-brown with a tan fringe (Powell and Opler, 2009).

The Mythimna unipuncta larvae has a pale brown head with green tinge and mottled with dark brown. The larvae body is smooth, almost hairless, variably yellowish-green to brown to dark gray, and with several dark stripes interspersed with pale lines along top and sides (Powell and Opler, 2009).

Shropshire and Tallamy (2025) provide a list, with synonymies, of 13,055 described native, exotic, and occasional straying Lepidoptera species of North America, north of Mexico; known but undescribed taxa, taxa with unresolved taxonomy, and excluded species are also included. The main manuscript includes links to supplementary materials, including a reference list for Lepidoptera of North America north of Mexico, and a filterable spreadsheet with information on taxonomy, synonymy, size ranges of species, distribution by state, province, and country with references, and host-plant Family and Genus associations with references.

Mythimna unipuncta adults fly from March to November in the south, and April to October in the north (Powell and Opler, 2009).

Mythimna unipuncta prefers fields, gardens, meadows, and waste places (Powell and Opler, 2009).

Shropshire and Tallamy (2025) provide a link to a supplemental filterable spreadsheet with information on host-plant Family and Genus associations with references for all Lepidoptera species of North America, north of Mexico.

Mythimna unipuncta larvae are generalist feeders on many species of plants including alfalfa, corn and other grains. They also feed on grasses, vegetables, many weeds and other wild plants, the leaves of fruit trees, and ornamentals (Powell and Opler, 2009).