Tawny Emperor larvae hibernate in the leaf litter under hackberry (Celtis spp.) plants.
This species has a limited range in New York. It is likely a permanent resident in southeastern New York, although individual colonies can be transient. Its status is uncertain elsewhere.
The short-term trends are unknown, although this species could increase or stabilize with a warming climate.
The long-term trends are unknown.
The threats include habitat destruction, leaf raking, and Gyspy Moth (Lymantria dispar) spraying. Larvae of this species were documented to be highly sensitive to Bt (Bacillus thuringiensis - a bacterial biological control used on Gypsy Moths) (Peacock et al. 1998). Like many gregarious species, population numbers can fluctuate greatly, partially due to parasitism, and small colonies may not persist in some years. Cold winters without snow cover might also eliminate populations in New York.
Leaf litter under hackberries (Celtis spp.) should be left undisturbed from mid-August into May since the larvae spend most of the year hibernating there (Dale Schweitzer).
This species is potentially found in any shaded habitat that contains hackberry (Celtis spp.). Although it does not require pristine habitat, it would would not be likely to be found on lawns. Shapiro (1974) indicates that habitats are generally bottomlands in New York.
This species has been found in the southern counties as far north as Tompkins County. It turns up most often in the southeastern Hudson Valley counties near New York City, including Long Island. This species can be reliably seen in some places (Shapiro 1974, Glassberg 1993) and is almost certainly a permanent resident in southeastern New York, although individual colonies can be transient. Its status is uncertain elsewhere. The range could expand with a warming climate.
As the species is now defined, it occupies most of the range of the eastern hackberries (Celtis spp.), from Connecticut to southern Minnesota south through most of Florida and Texas and well into Mexico, west through northern Mexico and southeastern Arizona (Brock and Kaufman 2003).
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.
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.
The larvae and adults can be identified from available books and the eggs can be identified by an expert.
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.
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.
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.
The time of year you would expect to find Tawny Emperor reproducing, larvae present and active, and pupae or prepupae present in New York.
Asterocampa clyton (Boisduval and Le Conte, )
Allen, T.J., J.P. Brock, and J. Glassberg. 2005. Caterpillars in the field and garden. Oxford University Press, New York. 232 pp.
Brock, J. P., and K. Kaufman. 2003. Butterflies of North America. Kaufman Focus Field Guides, Houghton Mifflin Company, New York, NY 284 pp.
Glassberg, J. 1993. Butterflies through binoculars: A field guide to butterflies in the Boston-New York-Washington region. Oxford University Press: New York. 160 pp.
Glassberg, J. 1999. Butterflies Through Binoculars: The East. Oxford University Press, New York, New York. 400 pp.
Gochfeld, M. and J. Burger. 1997. Butterflies of New Jersey. Rutgers University Press: Rutgers, New Jersey. 327 pp.
Iftner, D. C., J. A. Shuey, and J. V. Calhoun. 1992. Butterflies and Skippers of Ohio. Ohio Biological Survey Bulletin. New Series, Vol. 9, no. 1, xii + 212 pp., 40 color plates.
New York Natural Heritage Program. 2020. New York Natural Heritage Program Databases. Albany, NY.
O'Donnell, J.E., L.F. Gall., and D.L. Wagner, eds. 2007. The Connecticut Butterfly Atlas. State Geological and Natural History Survey of Connecticut, Department of Environmental Protection, Hartford. 376 pp.
Peacock, J. W., D. F. Schweitzer, J. L. Carter, and N. R. Dubois. 1998. Laboratory Assessment of the effects of Bacillus thuringiensis on native Lepidoptera. Environmental Entomology 27(2):450-457.
Shapiro, A.M. 1974. Butterflies and Skippers of New York State. Search 4:1-60.
Wagner, D.L. 2005. Caterpillars of eastern North America. Princeton University Press. Princeton, New Jersey. 512 pp.
Information for this guide was last updated on: December 20, 2007
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Asterocampa clyton. Available from: https://guides.nynhp.org/tawny-emperor/. Accessed March 30, 2020.