Rare Species Guide

  Basis for Listing

There are two distinct populations of the species Hesperia leonardus in Minnesota, with geographically separated ranges. One, which occurs in the western part of the state, belongs to the subspecies H. l. pawnee, known as the Pawnee Skipper, a Great Plains butterfly. The population east of the prairie and parkland provinces (Eastern Broadleaf Forest and Laurentian Mixed Forest provinces) in Minnesota is best treated as belonging to subspecies H. l. leonardus, which has an extensive range in eastern North America. The name Leonard’s Skipper was historically limited to this eastern form. The two subspecies are very different in appearance and were, until recently, treated as different species. The eastern Minnesota population and Roseau County, along with the Leonard’s population in much of Wisconsin and western Iowa, exhibit a noteworthy amount of variability in color and pattern but are more like typical Leonard’s farther east than like Pawnee. This variability indicates substantial recent or continuing gene flow between the two populations, supporting their treatment as subspecific variants of a single species (Scott and Stanford 1981; Spomer et al. 1993). However, the western Minnesota population is typical Pawnee Skipper, with no obvious evidence of gene flow from Leonard’s. Populations in the southeast corner of Manitoba are reported to be typical subspecies leonardus (Klassen et al. 1989), and a few specimens collected in eastern Roseau and Lake of the Woods counties appear to be this subspecies as well.

Habitat loss is a serious threat to Leonard's Skipper in Minnesota. The sand prairie and barrens habitats of Leonard’s Skipper in eastern Minnesota have always been patchy, and the same is true of the bluff prairie habitat in the southeast part of the state. An increasingly wetter climate and removal of fire from the landscape have led to woodland and forest taking over open habitats that Leonard’s Skipper needs. Well-drained sandy soils are attractive sites for housing and commercial development. None of the sites that have been set aside for the protection of this species provide enough habitat to support large skipper populations, leaving these isolated colonies at risk of extirpation. For this reason, Leonard's Skipper (which includes both Leonard’s Skipper and Pawnee Skipper subspecies) was listed as a special concern species in Minnesota in 1996.

  Description

Leonard's Skipper is a typical member of the "branded" skippers, or subfamily Hesperiinae. It is a smallish butterfly with a robust body, narrow angular forewings, and shorter broader hindwings. Forewing length (base to apex) of males is 1.50-1.65 cm (0.59-0.65 in.). Females are slightly larger with more rounded wings. The antennae are relatively short with clubbed ends that have a sharp, recurved tip. Leonard's Skippers are fast fliers with a very rapid wing beat that appears as a blur to the human eye.

Males and females differ in wing markings, most notably on the upper surface of the forewings. Males have a narrow black "brand" of specialized scent scales used in courtship centrally placed along the long axis of their forewing. Females lack this but instead have a pattern of light-colored squarish spots on a darker background; these are mostly opaque, only the largest is sometimes slightly translucent. Males have a brownish-orange ground color on the upper surface with variably extensive dark margins, though typically the darker areas dominate. Females are typically almost entirely dark brown above with strongly contrasting pale yellowish spots on both fore and hindwings. In Minnesota populations of Leonard’s Skipper, the underside of the hindwing varies from dark rust-red to ochre, and the band of pale spots is commonly present, varying in size and sometimes absent.

The late summer flight period of Leonard’s reduces the problem of distinguishing it from other similar skippers. A superficially similar skipper, the Sachem (Atalopedes campestris), regularly produces a late-summer brood in southern Minnesota. Males of this species have a predominantly orange forewing upper side with a broad black patch surrounding the brand; females have a continuous band of pale spots on the underside of the hindwing that forms a sharply angled chevron. The larger forewing spots of Sachem females are obviously translucent, while these are opaque or faintly translucent in females of Leonard’s. In far northern Minnesota (Roseau County), the Laurentian Skipper (Hesperia colorado laurentina) flies at the same time as Leonard's and in the same habitats, but it is smaller, and the ground color of the hindwings underside is a more greenish-brown than the reddish brown of Leonard's.

  Habitat

Leonard's Skipper is strongly associated with dry, open habitats on sand, including prairie, savanna, and openings in woodlands (southern, central, and northern). Dominance by herbaceous species characteristic of native prairie seems to be an important factor.

  Biology / Life History

Leonard's Skipper has a single annual generation. Eggs are laid in late summer and hatch in about ten days. After a short period of feeding, young larvae (first or second instars) enter diapause until the following spring, when feeding and growth resume. Larvae complete their growth in late July and pupate; adults emerge in August. Males emerge on average a few days earlier than females and quickly begin seeking mating opportunities by perching on taller stems in the prairie and pursuing insects that fly by. Receptive females respond to pursuit by descending into the vegetation, where mating occurs. Females probably mate shortly after emergence and seldom remate, based on what is known about other species in the genus Hesperia. Eggs are matured steadily during the female's lifetime and laid singly. Based on data from the similar Dakota Skipper (Hesperia dacotae) (Dana 1991), potential fecundity is probably 200-250 eggs. Female longevity has not been determined, but it is probably less than two weeks.  In Minnesota, adults are rarely encountered away from native prairie, savanna, or woodland habitats, suggesting the incidence of dispersal out of these is low.

Larvae feed on grasses, but specific preferences have not been determined. Pawnee Skipper females in southwestern Minnesota have been observed ovipositing on seven different grass species as well as on three forb species (personal observation). Of the two observed ovipositions by Leonard's, one was on a grass and one on a forb (personal observation). It is probable that this skipper, like the Dakota Skipper and the Ottoe Skipper (Hesperia ottoe), feeds opportunistically on several grass species in nature. Like other skippers in this genus, the larvae construct shelters from which they forage, and structural suitability of the grasses for shelter construction may be the most important determinant of use. The details of shelter location, whether up in the foliage or at the base of the plant or even underground, are not known. Adults are avid seekers of nectar; blazing stars (Liatris spp.) are especially attractive, but goldenrods (Solidago spp.) and asters (Symphyotrichum spp.) are also commonly visited. Males also imbibe from wet soil (“puddling”).

  Conservation / Management

Habitat loss is the primary threat to Leonard's Skipper in Minnesota. Habitat remnants for Leonard's Skipper are severely threatened by residential and commercial development. These habitats are also threatened by succession to woodland and forest in the absence of fire or other disturbance. This is a threat even for habitat that is protected from development.

Use of herbicides to control thistles (tribe Cardueae) and other unwanted plants can also eliminate adult skipper nectar sources. Insecticides are a potential threat; oaks are among the preferred larval hosts of the Spongy Moth (Lymantria dispar) and recent efforts to manage spongy moth with Bacillus thuringiensis kurstaki (Btk) in Minnesota have occurred at or near Leonard’s Skipper populations.

The use of prescribed burning to maintain the prairie and savanna habitats of this skipper can also pose a threat. There is circumstantial evidence that fire can cause high mortality to larvae (Swengel 1998; Swengel and Swengel 1999). Unless the shelters of small overwintering larvae are buried in the soil or deep in the bases of grass clumps, high mortality during fall and spring burns should be expected. Experimental investigation is needed. Factors that influence fire intensity, such as fuel load, fuel moisture content, and ambient temperature, are important to consider in planning burns. Subdividing a site and burning the units in a rotation that leaves enough larval habitat unburned to assure population survival and recolonization of burned areas between burns is recommended. This may be difficult for small sites. Haying may provide a suitable option in these cases.

Because most sites that support this skipper are small and isolated from others, their small colonies are at high risk of extirpation from both natural events (such as severe drought or hailstorms) and human caused ones (such as accidental insecticide application) as well as from the vagaries of normal population processes (for example, by chance all adults in one generation are males). Loss of genetic diversity may also be a concern.

Several programs and resources are available to land managers and landowners to help protect and manage remaining prairie parcels including the Native Prairie Bank Program, the Native Prairie Tax Exemption Program, and a prairie restoration handbook.

  Conservation Efforts in Minnesota

Leonard's Skipper occurs in a number of sites in Minnesota that are owned and managed by public agencies and private conservation agencies. These include several moderately large sites that support fair populations. The Minnesota DNR has sponsored or supported several survey efforts to find new Leonard's Skipper locations and update information for previously known locations. Guidelines for protecting skipper populations within a fire-management program are employed by most of the major owners of Leonard's Skipper habitat in Minnesota, and efforts have been made to educate other land managers. Data on the locations of colonies are maintained by the Minnesota DNR's Natural Heritage and Nongame Research Program and consulted during the state environmental review process so that projects can be modified to reduce or avoid harm.

  Authors/Revisions

Robert P. Dana, Ph.D. (MNDNR), 2025
(Note: all content ©MNDNR)