Hickory horned devil caterpillars look fierce and can be almost as big as a hot dog, but they’re harmless. They have green bodies (that become turquoise as they age) and lots of prickled, orangey horn-like structures on their heads. They’re so big and fierce-looking that even chickens — which usually love to eat caterpillars — have been known to stay away from them.
The caterpillars' scary appearance is a ruse, though, as the spines are not sharp and they do not sting. Eventually, this Hickory Horned Devil will pupate and emerge as a Citheronia Regalis moth.
Larvae have been reported from a variety of host tree species. They are commonly found on walnut (Juglans nigra), butternut or white walnut (Juglans cinerea), and a variety of hickories including pecan. Other hosts commonly listed are persimmon (Diospyros virginiana), sweetgum (Liquidambar styraciflua), and sumacs.
As an adult the regal moth has a wingspan of 9.5 to 15.5 cm (Covell 2005). Females are larger than males. The forewings are gray to gray-green with orange veins and a row of seven to nine yellow spots near the distal margin. There also are single yellow discal and basal spots. The hind wing is mostly orange with a basal yellow spot and yellow patches (or spots) on the costal and anal margins. The hind wing may also have one to two rows of gray-green spots. The body is orange with narrow yellow banding.
Right Here in New Jersey
Right here in New Jersey, Tamke Tree Experts Vice President, Chris Hunt found a Hickory Horned Devil caterpillar on his own property. As they are rare to find this north in the New Jersey region, it typically is a species common to the deep south.