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Pearl Crescent

Physiodes tharos tharos (Drury, 1773)

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Adult photo (Click to enlarge)
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Adult photo (Click to enlarge)
Distribution Map
Ohio county distribution
Records by Month
Flight period (Temporal distribution)

STATUS: Resident; common.

DISTRIBUTION/RANGE: Statewide (see map). This species has been recorded from all 88 Ohio counties.

HABITAT: This species is ubiquitous in open areas which contain nectar resources. Typical habitats include old fields, pastures, vacant lots, lawns, waste areas, prairies, fens, sedge meadows, alfalfa and clover fields, lake margins, and open woodlands.

HOSTPLANT(S): Not known in Ohio. Throughout its range, this species uses several species of asters (Aster spp.), particularly those of the subgenus Euaster (Shapiro, 1974; Oliver, 1980). Asters are common and widespread in Ohio.

ADULT ENERGY RESOURCES: Alfalfa, red clover, white clover, white sweet clover, black mustard, field pepper-grass, bouncing-bet, shrubby cinquefoil, cinquefoil, brambles, pale touch-me-not, wild carrot, common milkweed, butterfly-weed, Indian hemp, peppermint, black-eyed Susan, brown-eyed Susan, wing-stem, Jerusalem artichoke, dandelion, horseweed, small white aster, asters, Philadelphia fleabane, Canada thistle, tall ironweed, spotted Joe-Pye weed, and common boneset. Adults also take moisture from damp soil, sand and gravel, urine and fecal deposits, and carrion. This species is a common visitor to mud puddles.

FLIGHT PERIOD: Three to four broods per year, with peaks in May, July, and late August-early September (see graph). Extreme dates range from 18 April to 2 November.

SIMILAR SPECIES: The Silvery Checkerspot (Chlosyne nycteis). This species is also extremely similar to the Northern Pearl Crescent (P. pascoensis). In P. pascoensis, the thin linear markings on the ventral hindwings are usually pale orange whereas in P. tharos these markings are usually black. Similarly, P. pascoensis has a pale marginal patch surrounding the crescent spot on the ventral hindwing but in P. tharos the area surrounding the crescent spot is usually black. Dorsally, P. pascoensis has a more yellowish postmedial band on the forewings and a relatively clear, orange band on the hindwing (Paul A. Opler, pers comm, 1988). Although these two species can be distinguished by antennal club coloration in most regions (orange in P. pascoensis; black in P. tharos), this character is unreliable in Ohio. Questionable specimens should be determined by an authority. Because P. tharos and P. pascoensis have only recently been recognized as distinct species (Oliver, 1980), reliable characters which separate these species over their entire ranges have not yet been discovered. They are genitalically similar, and both species are phenotypically variable.

GENERAL COMMENTS: This is one of Ohio's most common butterflies and is a familiar sight throughout the State in almost every open habitat. It is particularly abundant in old fields where there is a proliferation of nectar sources.

Males of this species seem very aggressive, and are often observed chasing other insects. This is probably an investigative behavior associated with mate location. The flight of this species is erratic and fairly rapid for its size. Adults alternate short periods of active flight with periods of gliding and usually fly close to the ground. When not patrolling, males are most often encountered while they visit flowers or moist soil. Both sexes perch with their wings held outstretched.

There are two phenotypes of this species, both of which are extremely variable. The cool weather form 'marcia' (W. H. Edwards, 1868), which occurs in the spring and rarely in the autumn, has dark brown and white markings on the ventral hindwings. The warm weather form 'morpheus' (Fabricius, 1775), which occurs in the summer, has more yellow or cream-colored ventral hindwings. Females of both forms are larger and more variable than males. The melanic aberration 'packardii' Saunders, 1869, has been captured at various locations throughout the State.

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