Hackberry Emperor (Asterocampa celtis) (Boisduval and Le Conte, 1835)
Diagnosis: In this medium-sized (wingspan: 39 to 47 mm) species the males are dark tawny to grey brown above, while females are a lighter tawny colour. Both sexes have a complex pattern of spots. The forewing tips are dark with a white spot. There is an irregular series of white spots on the outer portion of the forewing and a single large black spot near the outer margin below the middle. There is one solid dark bar and two dark spots near the wing base along the front edge of the forewing.
Subspecies: Only the nominate subspecies is found in Canada.
Range: Because it is restricted to areas where hackberry grows, it is found in Canada in the St. Lawrence River Valley, east to Beauport, Quebec, and in southwestern Ontario. There is a single record from Souris, Manitoba.
Similar Species: The Hackberry Emperor is best distinguished from the Tawny Emperor (A. clyton) by the one solid dark bar and two dark spots near the front edge of the forewing; these form two dark bars in clyton. In celtis the pale spots on the forewing are white, whereas in clyton they are pale yellow. [compare images]
Early Stages: The bright-green larvae have lengthwise stripes of yellow, a broad one on each side ofthe back and two narrow ones on each side, one at the top and one at the middle of each side; theupper one is usually wavy. They have two short horns at the rear and a pair of yellow branching hornson the top of the head. They feed on young leaves of hackberry (Celtis occidentalis and C. tenuifolia).
Abundance: This is usually an uncommon and localized species in most of its limited Canadian range. However, it can be common at Point Pelee, Ontario, where hackberry is abundant.
Flight Season: There are probably two flights in eastern Canada, but this is difficult to determine since in some areas there are only single records. At Point Pelee the first brood flies in July and early August, and the second is on the wing from mid-August to mid-September (Wormington, 1983).
Habits: The Hackberry Emperor is fast flying and aggressive, "buzzing" other species and even people. It should be looked for on or around its foodplant trees, often on the ground at fruit or animal droppings.
© 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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