This story was originally published in October 2022.
With its colorful body and bright red horn, the bedstraw hawk-moth caterpillar looks like it crawled right out of an “Alice in Wonderland” story and not out of a patch of fireweed.
Despite its striking appearance, the bedstraw hawk-moth is one of Maine’s more innocuous insects, according to Jim Dill, pest management specialist with the University of Maine Cooperative Extension.
“They are really interesting, Dill said. “There is a pretty good color variation in the caterpillars that can be almost coal black with yellow spots and that red horn to bright green.”
Unlike its relatives in the Sphingidae family like the tomato or tobacco hornworms, the bedstraw caterpillars pose no threat to gardens or crops.
“As a moth they are flying most of the summer and they are a good sized moth with a couple of an inch wingspread with reddish underwings and black or brown colorations on the bodies,” Dill said. “Like the name implies, the caterpillars feed mostly on bedstraw, which is a very low growing weed, so it’s not really a pest.”
They will also feed on fireweed, Dill said.
As far as that red horn on the caterpillars’ anterior end, Dill said it appears to be purely ornamental.
“You see them on all the hornworms,” he said. “They don’t use them to sting at all.”
This is the time of year people are most likely to see the bedstraw caterpillars as they are out and about looking for a place to burrow into the ground to pupate.
“They are pretty common in Maine,” Dill said. “But when people first see them, they are ‘Oh my gosh, what is this thing?’ which is understandable given their color and that horn.”
