|scientific name Phyciodes tharos |
common name Pearl Crescent
Grasslands and dry meadows of the prairie and parkland regions.
Double brooded in Alberta, flying primarily in June and again in August.
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.
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).
Not of concern
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).
Occurs throughout eastern North America, north to southern Ontario and southern Alberta (Scott 1986).
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