Nymphalidae (brush-footed butterflies)
The hackberry emperor is similar to the closely related, but less common tawny emperor (A. clyton), but it is a more neutral tan, while the tawny is more rust-colored. Looking more closely, the upperside cell (the discal cell is the narrowly oval section at the front core of the forewing) of the hackberry emperor has one unbroken dark bar, while the inner dark "bar" is broken into 2 offset spots (this region on the tawny emperor has two unbroken dark bars). The dorsal (top) forewing tips are black with white spots; there is also a distinct black eyespot on the forewing. Seen from below, the hindwing has a row of eyespots: blue spots surrounded by black, yellow, and brown concentric rings.
Larvae are similar to those of the tawny emperor: green with yellow-green and white stripes; the last segment is forked. The head is ringed with small fingerlike projects, and 2 larger projections on top of the head fork and resemble miniature deer antlers.
Similar species: The tawny emperor, from above, doesn’t have white spots on dark forewing tips, lacks the black eyespot, and has two unbroken bars at the leading edge of the forewing, not a bar and two spots. Below, its hindwings have only smudgy-looking eyespots.
Wingspan: 1½–2¼ inches.
City yards, parks, and wooded areas. Always associated with hackberry trees, which are widespread in our state (Missouri has three species of hackberries). Many people see males of this butterfly perching, head-down, on trees, bushes, the sides of houses, and other tall objects, darting out at passing butterflies, animals, and people. They are fast, erratic flyers.
As both the common and scientific names suggest, hackberry trees (genus Celtis) are the host plants for the larvae of this species. In Missouri, this includes the common hackberry, C. occidentalis, as well as sugarberry (or southern hackberry), C. laevigata.
The adults seldom visit flowers, but they do absorb nutrients from tree sap, rotting fruit, carrion, animal droppings, and damp sand or muddy ground. This is one of several butterflies that are attracted to sodium in human sweat, so they often alight on people.
Adults fly from May through September. Males perch head-down on tall objects in sunny, open locations waiting for females to approach. Females deposit eggs in masses, and the larvae are gregarious when young, seemingly swarming on leaves in feeding groups. Larvae burrow underground in order to metamorphose into adults. In the fall, groups of half-grown caterpillars attach themselves to rolled dead leaves. They overwinter in leaf litter. In spring, they move back into the tree canopy to resume feeding.
This delicately beautiful butterfly delights people throughout the eastern United States when it lands on our skin on hot days to absorb salts from our sweat. It only lasts a few moments, but time magically stands still.
The caterpillars are herbivores that graze on hackberry leaves. All stages provide food for predators. The larvae, hibernating on the ground in their rolled-up leaves, undoubtedly feed many hungry birds and mammals in the winter.
Butterflies, skippers, and moths belong to an insect order called the Lepidoptera — the "scale-winged" insects. These living jewels have tiny, overlapping scales that cover their wings like shingles. The scales, whether muted or colorful, seem dusty if they rub off on your fingers. Many butterflies and moths are associated with particular types of food plants, which their caterpillars must eat in order to survive.