Hackberry Emperor

The Hackberry Emperor is a member of the brush-footed butterfly family Nymphalidae, in the genus Asterocampa — a small group of "emperor" butterflies whose caterpillars feed exclusively on hackberry trees. It is widespread across the eastern and central United States wherever its host tree grows.

Unlike most butterflies, Hackberry Emperors rarely visit flowers for nectar. Instead, adults are famous for gathering at mud puddles, animal droppings, sap flows, and rotting fruit, and for their bold, curious habit of landing on people's skin or clothing to obtain salts and moisture.

Its close association with a single host genus and its distinctive behavior make it a familiar sight to naturalists in wooded parks and river corridors throughout its range.

• Medium-sized butterfly with mottled brown-tan upperwings marked by cream-white bands and spots.
• A single prominent black eyespot near the forewing tip is a key identification feature.
• Hindwing bears a row of small dark eyespots along the outer margin.
• Underside is paler gray-brown with a similar pattern, providing camouflage against tree bark.
• Most easily confused with the Tawny Emperor, which lacks the forewing eyespot and tends to be more uniformly orange-brown.

Found throughout the eastern and central United States and into Mexico, wherever hackberry trees (Celtis species) grow — river bottoms, woodland edges, parks, and suburban yards with mature hackberries. Adults are active from late spring through early fall, often perching on tree trunks with wings spread.

Adults are territorial and often perch head-down on tree trunks, darting out to investigate intruders before returning to the same spot. Rather than nectaring, they feed on tree sap, rotting fruit, animal dung, and mineral-rich mud, and are well known for alighting on sweaty skin or clothing. Caterpillars feed at night on hackberry leaves and rest camouflaged along leaf veins by day, occasionally basking gregariously in groups when young.

Eggs are laid in clusters on hackberry leaves, and young caterpillars often remain together in small groups through their early instars, which is unusual among butterflies. Later instars become solitary and develop the characteristic green, striped, horned caterpillar form. There are typically two generations per year in most of the range, with the final-generation caterpillars overwintering partially grown in curled, silked leaves at the base of the host tree.