Dog Star skipper (Polites sonora siris)

Category: Butterflies and moths
Common names: Sonora skipper
Ecosystems: Westside prairie
Vulnerability to climate change (More details)


If you see this species, please share your observation using the WDFW wildlife reporting form. Providing detailed information such as a photo and exact coordinates will improve the confidence and value of this observation to WDFW species conservation and management.

The population of the Dog Star skipper (a Sonora skipper subspecies) in Washington is critical and is considered to have a declining trend. This butterfly is recognized as "Species of Greatest Conservation Need" throughout its range due to the small number of isolated populations, specialized and restricted habitat, and known threats to its habitat. Research is needed to more accurately quantify specific habitat requirements including vegetation structure, food plant size and density, and key habitat features.

Description and Range

Physical description

Sonora skippers are small, tan butterflies; their wingspan is a slightly more than one inch. This butterfly has small, rectangular cells in a symmetrical semi-circular pattern enclosing a basal spot on the underside of its hind wing. The butterfly is difficult to identify and may be confused with the mardon skipper.

Ecology and life history

The Dog Star skipper inhabits glacial outwash prairies, forest glades, and road edges in southwest Washington lowlands. The hostplants (grass/sedge) for this species have not been identified, and habitat selection and suitability have not been studied. Hostplants feed caterpillars (larvae). Their primary nectar plants are unknown.

These skippers complete a single life cycle annually (univoltine). They are sedentary butterflies and do not migrate; instead, the species inhabits sites year-round (as egg, larva, pupa and adult), typically moving within only a few hundred meters of their natal locations.

Adults emerge from their chrysalids (pupae) during June through July. Males begin emergence first, followed by females; late-season individuals are primarily or solely females. Weather influences butterfly emergence and the flight period duration, with wet or cold conditions delaying emergence. 

Both males and females feed by using their long proboscis to sip floral nectar.

Male skippers seek mates by perching on low vegetation and then darting out to inspect passing butterflies. Males that detect females commence courtship behavior; when males detect another male they engage in a territory defense behavior of tight, upward spiraling flight.

Females search for egg-laying sites by slowly flying and hovering just above hostplant vegetation and then depositing single eggs.

Skipper larvae conceal themselves in silken shelters and primarily feed at night. Sonora skippers are members of the Hesperiinae subfamily, whose larvae create shelters formed by webbing their hostplant grass blades together, and their prepupal larvae construct strong silken shelters in hostplant grasses in which pupation occurs. Sonora skippers overwinter as larvae.

Geographic range

Overall, the range of the Dog Star skipper is in southwest Washington; the butterfly occur in a few small, isolated populations. They inhabit glacial outwash prairies that have been reduced to less than three percent of historical cover. Occurrence has been documented in Grays Harbor, Mason, and Thurston counties.

Climate vulnerability

Sensitivity to climate change


There is limited information on the sensitivity of the Sonora skipper to climate change. As an occupant of forest edges, prairies, meadows and other open sites, this species may exhibit sensitivity to fire, which can help maintain open habitat conditions. However, similar to other prairie butterflies, fire may cause adult and/or larval mortality. It likely exhibits some physiological sensitivity to climate conditions, as population numbers fluctuate yearly, but more information is needed.

Confidence: Low

Exposure to climate change


  • Altered fire regimes
Confidence: Moderate


This species is identified as a Species of Greatest Conservation Need (SGCN) under the State Wildlife Action Plan (SWAP). SGCN-classified species include both those with and without legal protection status under the Federal or State Endangered Species programs, as well as game species with low populations. The WDFW SWAP is part of a nationwide effort by all 50 states and five U.S. territories to develop conservation action plans for fish, wildlife and their natural habitats—identifying opportunities for species' recovery before they are imperiled and more limited.

Conservation Threats and Actions Needed

  • Invasive and other problematic species
    • Threat: Invasive plants, those currently here, and many yet to come in the future, out-compete native grassland species and otherwise make habitat unsuitable
    • Action Needed: Using herbicide, fire, and mechanical methods to restore native prairie

See the Climate vulnerability section above for more information about the threat posed by climate change to this species.



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Other resources