Friday, June 8, 2012

Butterfly of the Week

Horace's Duskywing

Erynnis horatius (Scudder and Burgess 1870)
Status: Uncommon breeding resident.
Flight: Apparently triple brooded in Iowa, with the first brood flying from late April to early May, the second from early June to late July, and the third from mid August to early September.
Distinguishing features: Erynnis horatius is close to E. juvenalis in appearance but is more uniformly brown and lacks the two sub apical pale spots on the lower hind wing. Most of its flight occurs during the summer months, long after E. juvenalis has passed. Both of these species are larger than E. baptisiae and E. lucilius. Wingspan: 3.5-3.8 cm.
Distribution and habitat: Map 92. Scattered and rare throughout the state. No clear habitat preferences have been noted; it has been encountered from a wide variety of natural and altered habitats. In western Iowa it may be more common along oak-lined stream corridors.
Natural history: Although E. horatius has a wide distribution in the United State, Don C. MacNeil (in Howe 1975: 525) notes that it is "almost absent from the Great Plains." Its large have been reported to eat various oak species.
Questions: Why is E. horatius so much more uncommon in the state that E. juvenalis? What are its preferred habitats, if any? Is it more mobile that E. juvenalis?

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