Length: typically 7 mm
Older works put genus Winthemia in subfamily Goniinae.
Winthemia is a common and widespread genus. Its life history includes the parasitizing of caterpillars. Among the hosts of various Winthemia species are Cecropia Moth larvae, Tobacco and Tomato Hornworms, Fall Armyworm, Corn Earworm, and Green Cloverworm.
Other reported hosts include Weevils and Wasps (Arnaud, 1978).
Winthemia has recumbent hairs on the third and fourth abdominal tergites.
DeLoach and Rabb (1971) described the life history of one Winthemia species, Winthemia maducae, emphasizing its parasitizing of the Tobacco Hornworm, Manduca sexta. The female flies laid an average of eight eggs on final instar caterpillars. Hatching of the eggs seemed not tied to a particular number of days, but rather coincided (by an unknown mechanism) with the host’s prepupa molting, "at which time the parasitic larvae entered the host pupa before its integument hardened."
The fly larvae developed within the hornworm pupa for seven days, then exited the pupa and underwent its own pupation within two days, typically in the upper several inches of soil. The pupal period averaged sixteen days, with the females typically emerging after the males. Oviposition was observed four days after the adult’s emergence. The overall development took about 37 days. The authors noted that while the sex ratio in the laboratory was equal, in the field the researchers found only females, suggesting that the males may live most of their lives in a different habitat from the females.
Insects of West Virginia