Pearl Crescent

Phyciodes tharos is a small to medium sized butterfly that is 16-18 mm in length, with a wingspan of 3-4 cm. There are characteristic traits that differentiate males from females. Female wing coloration is generally darker than in males, with paler median spots. Males have black antennal knobs, which females lack altogether. The butterfly's coloration is black and vibrant orange, but the markings can vary geographically and can change from season to season. Spring butterflies tend to be darker than summer generations and have grey mottled hindwings. Typically, the upperside of the wings are brighter orange with marks on the forewings. The underside of the hindwings are an unmarked orange-brown to gray-brown, with a white cresent along the outer margin. Eggs are green. Larvae are chocolate brown, have a white mid-dorsal line, and are covered with tiny white dots. As larvae develop, caterpillars turn black and gain yellow bands on thier sides and spots along their back. The caterpillar also has eight rows of brown-yellow spines.

Range length: 16 to 18 mm.

Range wingspan: 3 to 4 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes colored or patterned differently; sexes shaped differently

The pearl crescent prefers open, moist, and sunny places. It is commonly found along roadsides, fields and meadows, open pine forests, and vacant lots.

Habitat Regions: temperate

Terrestrial Biomes: savanna or grassland ; forest

Other Habitat Features: agricultural

The pearl crescent butterfly ranges from Alberta, Canada down south along the east coast of the United States into Mexico. It has also been seen in Montana, Wyoming, Colorado, New Mexico, Arizona, southeastern California, and Mexico. This species is not found in the Pacific Northwest.

Biogeographic Regions: nearctic (Native )

The adult uses a siphoning technique to feed on nectar from an array of flowers including dogbane, swamp milkweed, shepherd's needle, asters, black-eyed susans, thistle, gloriosa daisies, white clover, and winter cress. The butterfly siphons nectar out of the flower by using its coiled tongue (proboscis). Caterpillars have chewing mouthparts used to eat leaves and other materials off of plants.

Plant Foods: leaves; nectar; flowers

Primary Diet: herbivore (Folivore , Nectarivore )

This species of butterfly has no known economic importance.

This butterfly has little economic significance, although larvae can be a nuisance, eating the leaves off of their host plants.

As larvae develop, caterpillars turn black and gain yellow bands on thier sides and spots along their back.

Development - Life Cycle: metamorphosis

The pearl crescent butterfly is in no danger of extinction, although it may be rare in parts of its range, especially at the periphery.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

The pearl crescent is one the most common of 700 species of butterflies in the United States and Canada. Many subspecies of Phyciodes tharos have been identified. Phyciodes tharos arctica, found in Newfoundland, has a deeper more orange and yellow underside. Phyciodes tharos tharos, a subspecies found in New York, is lighter than the subspecies found in Newfoundland. Other subspecies found in Colorado and Washington are Phyciodes tharos morpheus and << Phyciodes campestris>>. Similar species to P. tharos are the Silvery Checkerspot and Phaon Crescent.

During courtship, the male pursues the female butterfly while he is patroling the host plant. If the female is flying, she lands, keeping her wings spread. Next, the male lands behind her, possibly displaying his wings and on occasion fluttering them. With his wings partially opened he crawls under her hindwings to mate. For highly receptive females, which are usually motionless, the male rarely displays or flutters before mating. On the other hand, an unreceptive female will close her wings, possibly causing the male to leave. If the male doesn't fly away, the female may raise her abdomen (so he cannot join), turn and crawl away, drop down into vegetation, or fly away to escape.

Females lay eggs in masses of 20-200 (average 36), sometimes two or three layers deep on the underside leaves of a host plant (usually aster leaves).

Range eggs per season: 20 to 200.

Average eggs per season: 36.

Key Reproductive Features: semelparous ; sexual ; fertilization (Internal ); oviparous

After oviposition, there is no further parental involvement.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female)

Phyciodes tharos is resident in the eastern and southern United States, as far north as Alberta and south to southern Mexico and Bimini (Scott 1986). Habitats are moist meadows, moist fields, moist prairie and streamsides. Host plants are herbaceous and largely restricted to one genus, Aster (Compositae). Eggs are laid on the host plant in clusters with between 20-300 (average 63) eggs per clutch. Individuals overwinter as X. There is a variable number of flights each year depending on latitude with multiple flights all year in the south, and two flights in the far northern part of the range with approximate flight times late May-Aug30 (Scott 1986).

Not of concern

Double brooded in Alberta, flying primarily in June and again in August.

Occurs throughout eastern North America, north to southern Ontario and southern Alberta (Scott 1986).

"The crescents form a complex group of poorly understood species, partly as a result of the fact that they are often very similar in appearance. Extensive genetic research by Wahlberg et al. (2003) has not clarified the species relationships. Males of the Pearl Crescent have more extensive upperside black markings (the black forewing median line is usually continuous not broken) comapred to the Northern Crescent (P. cocyta), and the hindwing marginal pale yellow crescents are more prominent, resulting in a broken rather than a solid black margin. Compared to batesii, tharos has less black on the upperside, and the tip of the antennal club is black, white and orange, not black and white as in batesii. This character is not relaible for separating females of these species. Tharos females generally have a more distinclty marked underside than either cocyta or batesii females. Female crescents have more black markings on the upperside and paler orange spots in addition to the orange ground colour; they are best identified by association with males from the same population. Subspecies orantain, recently named by Scott (1998), describes our populations."

Grasslands and dry meadows of the prairie and parkland regions.

Scott (1998, 1994) gives detailed descriptions of the immatures. The pale green eggs are laid in clusters, and the larvae are dark brown, spiny and feed on leaf undersides. Partially grown (fourth instar) larvae hibernate (Scott 1998). Young larvae feed during the day, while older ones appear to be strictly nocturnal, resting in plant litter below the host during the day (Scott 1998).

The larval hosts are not known in Alberta. Larvae feed on asters (Aster spp.) in the west-central US (Scott 1998) and also in Manitoba (Klassen et al. 1989).

The pearl crescent (Phyciodes tharos) is a butterfly of North America. It is found in all parts of the United States except the west coast, and throughout Mexico and parts of southern Canada, in particular Ontario. Its habitat is open areas such as pastures, road edges, vacant lots, fields, open pine woods. Its pattern is quite variable. Males usually have black antenna knobs. Its upperside is orange with black borders; postmedian and submarginal areas are crossed by fine black marks. The underside of the hindwing has a dark marginal patch containing a light-colored crescent.

The wingspan is from 21 to 34 mm. The species has several broods throughout the year, from April–November in the north, and throughout the year in the deep south and Mexico.

ventral view Caterpillar Composite showing the variation in this species

Adults find nectar from a great variety of flowers including dogbane, swamp milkweed, shepherd's needle, asters, and winter cress. Males patrol open areas for females. The eggs are laid in small batches on the underside of host plant leaves of aster species (family Asteraceae). Caterpillars eat the leaves and are gregarious when young. Hibernation is by third-stage caterpillars.