June is well-known for the giant silk moths that emerge this month, but there are other large moths that are encountered as well, one of which is the Poplar Hawk-moth (Laothoe populi). Hawk-moths, also known as Hornworms (their larvae, which feed mainly on species of poplar, usually have a horn), are a type of Sphinx moth, which are known for their fast, enduring flight. One of the more familiar species of this family is the day-flying Hummingbird Hawk-moth, which can be seen hovering at flowers while sipping nectar with its proboscis.
Adult Poplar Hawk-moths, with wingspans as large as four inches, emerge in early summer. Their life is so short that they do not have a functional proboscis and do not eat, but concentrate on mating. Females extend a scent gland from the end of their abdomen to lure in the night flying males whose large claspers are frequently wide open as they fly in to lights around midnight. The moths mate and the females lay their pale green eggs on the leaves of poplars and willows, which the larvae eat once they hatch. Fully-grown caterpillars pupate and overwinter in shallow burrows in the ground.
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Abbott’s Sphinx Moth larvae feed on grape and Virginia creeper leaves during the night. During the day they tend to rest on the woody vines of the plants they are eating, and because they are well camouflaged, they remain hidden from most humans’ eyes. Both as larvae and adults, these moths are well equipped for survival. Older larvae have two color forms, one resembling unripe green grapes (in photo), and the other is brown and looks much like a branch. In their last stage, or instar, both forms have a rear eyespot which looks like a human eye, right down to the white reflection spot in it, which scares off potential predators. If the caterpillar is pinched or prodded, it squeaks and tries to bite the attacker. The adult moths, which emerge next summer after pupating all winter, also defend themselves with both color and behavior. They are brown with yellow bands on their underwings, which make them look something like a bumblebee, and when they fly, they create a buzzing noise. (Thanks to Heidi, Tom and Simmy Wetmore for photo op.)
Of all the insects I’ve found in milkweed patches over the years, the Hummingbird Clearwing is one of my favorites. It is a species of sphinx moth, named for its habit of hovering at flowers while it gathers nectar with its proboscis in a manner similar to that of hummingbirds. In fact, they are often mistaken for hummingbirds. The transparent wings, light brown thorax and dark chestnut abdomen are the field marks to look for. A diurnal moth, the Hummingbird Clearwing can often be found during the day in milkweed patches.