New York Natural Heritage Program
Tawny Emperor
Asterocampa clyton (Boisduval and Le Conte, [1835])

Identifying Characteristics [-]
Adults are easily identified at least if the upper side is seen. See any butterfly book. Larvae can also be separated. This species lays its eggs in large masses often two layers deep on the underside of hackberry leaves. These can often be identified by Lepidopterists. A. celtis lays eggs singly or nearly so.

Characters Most Useful for Identification [-]
The general color and details of the pattern are easily identifiable. See any butterfly guide. The larvae can be identified by the characters given by Wagner (2005) and Allen et al. (2005). The eggs are laid in large masses, often two layers deep, on the underside of hackberry (Celtis spp.) leaves. It should be noted, however, that there are some other moths, notably several Arctiidae, that may lay egg masses on hackberry.

Best Life Stage for Proper Identification [-]
The larvae and adults can be identified from available books and the eggs can be identified by an expert.

Behavior [-]
The males are most active earlier in the day than the more common Hackberry Emperor (Asterocampa celtis). The larvae are gregarious, except in the late instars, and multiple individuals may be found in a slightly rolled leaf.

Diet [-]
The larvae feed only on various species of hackberry (Celtis spp.). The adults rarely visit flowers and their true feeding habits are not well known. They can be seen visiting sap oozes, fermenting fruits, and moist soil.
Tawny Emperor Images
click to enlarge
The Best Time to See
The main flight season in New York is July, although Glassberg (1993, 1999) indicates a few individuals in June, August, and September. The species has two or more annual broods through most of its range. The larvae hibernate in the third instar, which is probably reached in August, although a few continue development to produce a partial second brood. Second brood larvae enter hibernation in October (in New Jersey), but it is uncertain how late into the fall overwintering progeny of July adults remain active. The related A. celtis can enter winter diapause, also as third instar larvae, anytime from early July to October in New Jersey (D.Schweitzer) making both its second and third broods partial there. The larvae resume feeding in spring soon after the new leaves begin to appear, but the July flight season suggests they may not resume feeding until about mid or late May in New York. During warm weather, the pupal stage should take no more than two weeks.
Reproducing Larvae present and active Pupae or prepupae present
The time of year you would expect to find Tawny Emperor reproducing (blue shading), larvae present and active (green shading) and pupae or prepupae present (orange shading) in New York.