Length: about 14 mm; the male is smaller than the female
Black Locust is the only plant on which Thelia bimaculata can reproduce.
This species ranges from Wisconsin, Ontario, and Quebec to South Carolina and west to Colorado and Utah.
Funkhouser (1915) studied the life history of Thelia bimaculata and reported that the species typically took one month to go from egg to adult, but that the time varied considerably based on temperature. The species overwinters in the egg stage. In both New York and in Missouri, researchers have found that the species produces only one generation per year.
Funkhouser also produced careful drawings
of each instar of Thelia bimaculata. A photo of the fifth instar nymph is also posted on this site.
Right: The female is larger than the male and lacks the yellow markings. The female's horn tends to be straighter than that of the male.