I was standing at Pavilion 1 in Lancaster County Central Park one day early in June when a hackberry butterfly landed on my left arm. Immediately its long, straw-like mouth came out and I could feel it moving over my bare skin.
Though seeming to be companionable, the butterfly was lapping sweat from that arm for its salt, something this species of butterfly often does. I noted that it was a pretty butterfly, looking perfect and immaculate. It must have recently emerged from its chrysalis. Soon the brown and spotted butterfly darted away, satiated with the salt from my sweat.
Adult hackberry butterflies are unique because they don't sip nectar from flowers as most butterflies do. Rather, they eat rotting fruit, dung, carrion and tree sap.
Hackberry caterpillars feed on hackberry tree leaves, the reason this species' name. These larvae are tapered at both ends and green for camouflage among the leaves, with yellow spots and longitudinal lines. Two "horns" at the tail end and two branched spines like tiny antlers on the head help protect the caterpillars from birds and other predators.
Other kinds of butterfly larvae eat hackberry leaves, including those of American snout butterflies, question marks and mourning cloaks, making this tree more valuable to wildlife. American snout larvae are dark green with yellow side stripes. The "snout" on the butterflies is really lengthy mouth parts.
Question-mark caterpillars are black with white dots, orange spines and several orange or yellow stripes running lengthwise along the sides and back. The larvae of this species of butterfly eat leaves on hackberries, and other kinds of plants.
Mourning cloak larvae are black with white dots, black spines and eight red markings on the back. These caterpillars, too, eat tree leaves besides those of hackberries.
Hackberry trees flourish in rich, moist soils of deciduous woods, woodland edges, hedgerows and near bodies of water from southern Canada, south to Florida and west to Texas. Hackberry bark has many narrow, corky projections that look like mountain ranges. Hackberries are related to elm trees and help prevent soil erosion on floodplains near waterways.
Other kinds of wildlife eat certain parts of hackberry trees, making this tree even more beneficial to wildlife. White-tailed deer and cottontail rabbits ingest its buds and tender twigs in winter.
In summer, hackberry leaves are infested with hackberry gall psyllids- tiny, yellow insect nymphs that are wrapped in irritated leaf tissue called nipple galls and ingest the leaves' sap all summer. Adult psyllids resemble cicadas, but are much smaller. They emerge from their galls in September and over-winter in bark crevices. After mating in spring, females lay eggs on the underside of new leaves, which starts a new generation of hackberry gall psyllids.
By autumn, hackberry trees produce dark-purple, berry-like drupes that taste a bit like dates. A variety of birds, rodents and other kinds of mammals eat those drupes. The birds digest the thin pulp, but pass the seeds in their droppings, often miles from the parent trees, thus spreading the species.
Hackberry trees, and the animals that depend on them for food and shelter, make their habitats the more interesting year-round. This type of tree, like all of them, is valuable to nature.
Clyde McMillan-Gamber is a naturalist for the Lancaster County Department of Parks and Recreation. Email him at email@example.com.