Hornet Moth

Sesia apiformis — the hornet moth — is one of the most spectacular Batesian mimics in the insect world and one of about 1,400 species in family Sesiidae (the clearwing moths). The species has independently evolved a body plan that almost perfectly imitates a European hornet (Vespa crabro): transparent wings (most of the moth scales have been lost, leaving the wing veins and a few colored scale margins around the wing edges), a yellow-and-black-striped abdomen, a black-and-yellow patterned head and thorax, and a similar size and flight pattern to the actual hornet. The mimicry is so convincing that even experienced entomologists routinely misidentify the species in the field, and bird predators avoid her with the same reflexive caution they apply to actual stinging hornets — Batesian mimicry that derives protection from the host model species without requiring the moth to invest in actual venom or weaponry. Other Sesiidae species similarly mimic various wasps (currant clearwing — Synanthedon tipuliformis), bumblebees (bee hawkmoths — Hemaris), or honey bees (squash vine borer — Melittia cucurbitae). The Sesiidae mimicry strategy is one of the most-cited examples of Batesian mimicry in evolutionary biology curricula. The hornet moth life cycle is also remarkable: females lay eggs at the base of poplar (Populus) and willow (Salix) trees, and larvae bore deep into the tree heartwood, where they develop over 2-3 years before emerging as adults. The larval boring causes structural damage to host trees and can kill poplars in heavy infestations. Adults emerge in early summer, fly during the day (consistent with the wasp-mimicry strategy — most moths are nocturnal, but hornets are diurnal, so the mimicry only works in daylight), and live ~2 weeks.