As winter’s chill brings a marked downturn in insect activity here in the northeast, we turn to the “Bug of the Week” guest book to visit photographs sent by viewers during warmer times. Two wonderful images sent last year were marvelous moths belonging to the family Sphingidae, known as sphinx, hawk, and hummingbird moths. One picture sent by Joan was the beautiful Virginia creeper sphinx moth, Darapsa myron. The adult moth sips nectar with an exceedingly long straw-like proboscis. This remarkable appendage reaches astonishing length in some species. Charles Darwin discovered an orchid with a nectar receptacle almost a foot from the tubular opening of the flower. He predicted that a species of pollinator with an exceptionally long tongue must have evolved to service the orchid. Although Darwin never observed the pollinator, his prediction proved correct many years later when the giant hawk moth,
Xanthopan morganii praedicta, was discovered. Its tongue is more than nine inches long and it is the putative pollinator for the Malagasy orchid. Returning to our Virginia creeper sphinx, while the adult sips nectar from a variety of tubular flowers including honeysuckle, trumpet vine, and mandeville, the larvae consume leaves of several members of the grape family including grape, Virginia creeper, and porcelain berry. In Florida, several broods develop each year, but in Maryland only two broods are likely.
A Pandorus sphinx rests on a hydrangea. Photo credit Cindy Motsko.
The second interesting image comes from Cindy who found a wonderful Pandorus sphinx, Eumorpha pandorus, resting on the leaf of a hydrangea. This beauty likes to visit flowers at dawn and dusk. Like its cousin the Virginia creeper sphinx, it lays eggs on members of the grape family. This magnificent creature is found from Florida to Nova Scotia and it has several broods each year in the southern part of its range, but only one in the far north.
Sphingid caterpillars are called hornworms for obvious reasons.
To round out this episode, we visit one more sphingid moth, Hemaris thysbe, the hummingbird clearwing. Hummingbird moths are found throughout the United States and venture as far north as Alaska. Hemaris thysbe has two generations in southern states and one in its northern range. After feeding and mating, females lay eggs on the leaves of small shrubs and vines. Honeysuckles, snowberries, viburnums, hawthorns, and cherries are among its favorites. From the eggs hatch caterpillars that munch leaves. A dramatic horn adorns the rear end of many larval hummingbird, hawk, and sphinx moths giving these caterpillars the name hornworms. In addition to feeding like a hummingbird, some say that the greenish hairs on the back of the moth resemble the feathers of a ruby throated hummingbird. The flight and feeding behaviors in conjunction with the unusual coloration might be enough to confuse a hungry predator. While a tasty moth might make a fine meal, a predator might think twice about eating a hummingbird.
References:
Special thanks to Joan and Cindy for sharing images and inspiring this episode of Bug of the Week. Two marvelous references “Darwin’s Madagascan Hawk” by Gene Kritsky and “Caterpillars of Eastern North America” by David Wagner were references for this episode. To learn more about sphinx, hawk, and hummingbird moths please visit the following web sites.
http://www.butterfliesandmoths.org/species?l=3467
http://www.orchidsonline.com.au/node/7231
http://www.butterfliesandmoths.org/species?l=3437
http://www.butterfliesandmoths.org/species?l=3443