Arctiids — tiger and lichen moths, and their close relatives — are small to medium-sized moths that normally perch with their wings held rooflike over their bodies. Many are white, yellow, orange, red, and/or black, often in bold patterns: wide bands, tiger-like stripes, leopard-like spots, and so on. Some are wasp mimics. Others have more muted colors and patterns.
Arctiids used to be considered a family, Arctiidae — but now they’ve been reclassified as a subfamily, Arctiinae (with an n) in a newly created family, the Erebidae.
About 60 species have been recorded for Missouri, including the Isabella tiger moth (whose caterpillars are the famous woolly bears), acrea moth, fall webworm, great leopard moth, calico moth, yellow-collared scape moth, and several kinds of tussock and tiger moths.
Many arctiid caterpillars are usually hairy (many are called woolly bears), and some have stinging hairs. If you are unsure about an identification, or about your sensitivity to possible skin-irritating toxins, you should not touch any fuzzy caterpillars with bare skin.
The caterpillars of several species of lichen moths are camouflaged with texture and colors to look like the lichens upon which they feed.
Similar species: Note that some species in the Arctiinae are called “tussock moths” because their caterpillars have clumps of longer hairs protruding amid the shorter ones. Be aware that there is another subfamily in the Erebidae called the “true” tussock moths. It is confusing, but those “true” tussock moths, in subfamily Lymantriinae, used to be in their own family just as tiger and lichen moths did, and the groups are now joined in the new erebid family. Both groups share the “tussock” name because both can have caterpillars with the clumps of protruding, longer hairs.
Wingspan: ½–3 inches; varies with species.
Habitat and Conservation
Some arctiids are nocturnal, and some fly by day. Many are attracted to lights at night. As with other moth groups, many species have certain types of larval food plants with which they are associated. The females lay their eggs on or near these plants, and the caterpillars eat and grow on them.
Caterpillars in this family feed on a variety of woody and nonwoody plants, and several feed on lichens. Many feed on toxic plants, which render the caterpillars (and adult moths) toxic themselves. Adults of some species feed on nectar from flowers.
The new family (Erebidae) that the tiger and lichen moth subfamily now belongs to joins together several additional moth groups. Many of these (such as the underwing, or catocalid, moths) used to be members of the formerly huge family Noctuidae. The noctuid family continues, but minus those groups. Another distinct group, the tussock moths, are in the same situation as the tiger and lichen moths: they also used to be in their own family, but have now been reduced to a subfamily (Lymantriinae) in the new family Erebidae. These recent taxonomy revisions are confusing, but they represent a much greater clarity in our understanding of the true relationships among these animal groups.
The moth life cycle begins with eggs, which hatch and become caterpillars. Caterpillars eat, grow, and molt. Most overwinter as nearly grown caterpillars or in a cocoon containing caterpillar hairs. They emerge as adult moths, which mate and continue the cycle.
One of the most famous arctiids is the Isabella tiger moth, whose caterpillar is the famous “woolly bear.” Woolly bears have a long history in folklore as a weather predictor. The relative size of the orange and black portions supposedly determines how mild or severe the winter will be. Woolly bear caterpillars are conspicuous in fall as they search for hibernation sites; they wander again in the spring as they search for suitable food plants.
Although moths are stereotypically drab, most tiger and lichen moths are quite colorful and attractive.
Most moths are a favorite food of birds, most of which hunt moth caterpillars and adults by day, and bats, which hunt by night.
White, yellow, orange, and black colors announce the presence of inedible chemicals in many arctiid moths. Edible species gain protection by possessing similar color patterns. Warning colors defend against visual predators such as birds but are useless against bats. Arctiids, however, can hear the ultrasonic pulses of bats and take evasive action; some can emit return clicks that jam the bats’ sonar abilities.