Montana Field Guide

The Mesogona olivata forewing length is 15 – 20 mm. The ground color of the head, dorsal antennae, thorax, and forewing is variable, ranging from dull tan to reddish brown, gray-brown, or cream. The median area of the forewing and postmedian space at costa are darker than the ground color. The palpi have a mixture of ground color and dark scales. The forewing margin is crenulate. The forewing lines are double, smooth, and are filled with pale color. The basal line is sinuous and evident only near costa. The antemedian line is oblique and undulating. The outer line is dark. The postmedian line is smooth, and laterally convex. The subterminal line is sinuous and indistinct with a series of dark spots between the veins. The terminal line is thin and dark. The orbicular and reniform spots are large and pale with darker filling. The claviform spot is absent. The hindwing is variable with fuscous gray to reddish color that is always suffused with gray scales. Individuals from semi-desert locales tend to be pale while those from more mesic forest are darker (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.

Mesogona olivata adults fly from late August to November, with the earliest flight in the northern part of its range (Powell and Opler, 2009).

Mesogona olivata prefers dry open forest but also lives in shrub steppe and mesic forest habitats (Powell and Opler).

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.

Mesogona olivata larvae feed on deciduous shrubs and trees which include oak, hazel, alder, and antelope brush (Powell and Opler, 2009).