Montana Field Guide

{From Ferris and Brown 1981; Scott 1986; Layberry et al. 1998; Opler and Wright 1999; Glasberg 2001] Forewing 1.6-1.7 cm. Large. Uppersurface with extensive tawny orange and diffuse dark border (more extensive in females, giving a dull brown apearance), male forewing stigma with black gray felt; undersurface of hindwing yellow-orange, without median chevron of white spots, sometimes with a faint paler postmedian area.

One flight, late June through July, June in Kansas and Missouri (Scott 1986). June to early August (Glassberg 2001). Late June through July in the Rocky Mountain states (Ferris and Brown 1981). Late June to late July in north-central Nebraska (Dankert and Nagel 1988), mid-June to early August in North Dakota (McCabe and Post 1976).

Best determined from similar species by large size, earlier flight period, uppersurface extensive tawny orange and diffuse dark border, male forewing stigma with black or gray felt, undersurface of hindwing yellow-orange, without median chevron of white spots.

Non-migratory. Marked adults in Minnesota moved mean straight-line distances of up to 250 m over 7 days (Dana 1991).

Tall-grass to mixed-grass prairie, prairie ridgetops, dry fields, riparian woodland clearings (Ferris and Brown 1981; Scott 1986; Dankert and Nagel 1988; Dana 1991; Layberry et al. 1998; Opler and Wright 1999; Glassberg 2001; Swengel and Swengel 2015). Habitat in Montana not described but probably similar.

Larval food plants are grasses, including Andropogon (multiple species), Bouteloua (multiple species), Bromus, Dichanthelium, Leptoloma, Panicum, and Sporobolis, Poa in captivity; also possibly sedge (Carex) (Ferris and Brown 1981; Scott 1986, 1992, 2006; Dana 1991; Layberry et al. 1998). Adults feed on flower nectar (including Asclepias, Astragalus, Carduus, Cirsium, Cleome, Dalea, Echinacea, Heterotheca, Lactuca, Liatris, Lobelia, Monarda, Oxytropis, Phlox, Solidago, Trifolium, Verbena) and mud (Dana 1981, 1991; Swengel and Swengel 1999; Scott 2014).

Females lay eggs singly on host plant leaves, sometimes nearby on forbs (especially Echinacea angustifolia) (Dana 1981, 1991; Scott 1986, 1992, 2006). Eggs hatch 12-13 days post egg-laying (depending on temperature), develop in captivity to L4 instar in 41-94 days post egg-hatch (depending on temperature), overwinter (enter diapause) as L4 (sometimes L5) instar, exit diapause and develop to L5 instar and pupae in about 25-38 days, adults eclose (emerge from pupae) in about 12-22 days (Scott 1979, 1986, 1992, 2006; Dana 1991). Larvae eat host plant leaves (drop to ground and locate nearby host plant if egg deposited on non-host plant forb), early instars build silk-tied leaf-tube nest, move in late summer as L3 or L4 instars to buried shelters to overwinter, pupate in buried shelter following diapause (Scott 1986; Dana 1991). Males perch throughout the day, mainly on flowers near host plants (sometimes bare ground, low plants) on slopes and flats, sometimes patrol, awaiting, or searching for, passing females (Scott 1975b, 1982, 1986; Dana 1991).

Populations of this skipper should be conserved wherever found. Care should be taken in habitat management. Use of fire as a tool should be discouraged (Opler et al. 2010)

Conversion of tall-grass prairie to agricultural use has greatly reduced the habitat and numbers of the Ottoe Skipper.