Adult Nessus sphinxes have stout, furry-looking bodies with 2 whitish or pale yellow bands across the otherwise dark abdomen. The abdomen is tipped with a fuzzy tuft. Forewing upperside is brown with dark bands at the base, middle, and outer portions. The hindwings have a reddish-orange middle band and dark outer portion. The outer part of the hindwing’s leading edge is yellowish.
Caterpillars look different at each stage. Middle stages are green with tiny white dots and a lengthwise pale stripe along each side. Spiracles and the tail “horn” are black. The last stage before pupation is brown. The earliest stage is nearly transparent.
Wingspan: 1½ to 2¼ inches.
Habitat and Conservation
Adults are usually seen hovering like hummingbirds as they suck nectar from flowers. They are often attracted to lights at night. Missouri has several native vines in the grape family, and these are the Nessus sphinx’s principal food plants. Most Missouri grapes occur naturally in wooded areas, especially in lowland and riverside woods, so this is where the caterpillars, pupae, and newly emerged adults will be. Adult females, after mating, will seek out native grape species on which to lay eggs.
Larval food plants include members of the grape family, including peppervine and raccoon grape (Ampelopsis spp.), Virginia creeper (Parthenocissus quinquefolia), and other grapes (Vitis spp.). Also reported on “cayenne pepper,” which is just one of many varieties of Capisum annuum, so it probably can feed on other peppers as well.
Adult moths take nectar from a variety of flowers at dusk and also during the day.
There are apparently two broods in Missouri. In more southern regions, there may be multiple broods, and farther north, only one. The caterpillars of this species dig shallow burrows and pupate underground.
An earlier scientific name for this moth was Sphinx nessus. Even though the scientific name changed, the common name “Nessus sphinx” remained. The name “floridensis” means “from Florida,” and it was originally used for a proposed subspecies; when the scientific name changed, it became the new specific epithet.
In Greek mythology, Nessus was a centaur (a creature having the upper body of a person and lower body of a horse) who figured into the legends of Hercules. The character also appeared in Dante’s Inferno. In the 1990s, the name Nessus was bestowed on a newly discovered minor planet in our solar system, orbiting beyond Saturn.
Apparently the Nessus sphinx is not a serious pest on commercial vineyards. This may be because there are so many native grapes, including Virginia creeper, on which the larvae can feed.
It’s a safe guess that the bold black-and-yellow pattern on the abdomen plays a role in preventing some predators from attempting to capture this species. Even though it lacks a stinger, this moth certainly looks like a bumble bee.
A nifty experiment published in 2018 investigated the weird hissing, crackling sounds made by Nessus sphinx caterpillars when something pinches their body. These sounds apparently can startle potential predators (such as birds, rodents, and bats) and serve as a defense. The way Nessus sphinx caterpillars vocalize is quite unusual among insects: inside their bodies, they force air back and forth across a constriction between two chambers in their foregut, creating their freaky sounds by the same basic principle as the noise made by a steaming teakettle, or when you blow up a balloon, stretch the opening, then let air shriek out of its mouth.