Tawny Emperor (Asterocampa clyton) (Boisduval and Le Conte, 1835)
Diagnosis: In its wide range in the U.S., this butterfly is highly variable in colour and pattern, but in its very limited Canadian range, it lives up to its name, with a bright-tawny upper surface. It has two prominent black bars close to the front margin of the forewing. Wingspan: 40 to 64 mm.
Subspecies: The nominate subspecies occurs in Canada.
Range: Although it is widespread in the U.S., this species only occurs in Canada in southwestern Ontario, and only at Point Pelee and Pelee Island can it be expected regularly. The most northerly record in Ontario is from Goderich in Huron County.
Early Stages: The larvae are similar to those of the Hackberry Emperor (A. celtis) and also feed on hackberry. According to Scott (1986), the upper and lower yellow lines on the side are straight, unlike those in the Hackberry butterfly. Scott also states that the four longitudinal lines, normally yellow, are white in Ontario, but more material is required to confirm the consistency of this observation.
Abundance: The Tawny Emperor is less common and more restricted in range than the Hackberry Emperor (A. celtis).
Flight Season: Single-brooded and reported on the wing at Point Pelee from early July to late August.
Habits: This is essentially a woodland species in Canada, never straying far from the larval foodplant. It flies with the Hackberry Emperor (A. celtis) but, according to Wormington (1983), tends to fly and rest higher in the trees than that species.
Remarks: Scott (1986) reports that larvae of the Tawny Emperor feed on mature hackberry leaves, unlike the larvae of the Hackberry Emperor (A. celtis), allowing the two to occupy the same habitat without competing.
© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.
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