Ovarian development in adult Chrysops (Diptera: Tabanidae) in northern New England, with emphasis on Chrysops ater and C. mitis

Ovarian development in females of 10 species of Chrysops from northern New England was studied to determine whether the species developed eggs autogenously or anautogenously in the first gonotrophic cycle. The most abundant species collected were C. carbonarius Wlk. (ater Macq.) and C. mitis O. S. Of 41 females of the first species examined, 83% had follicles at stage 5 seven days after adult emergence, the rest having follicles at stages 3 and 4; the 50 females of C. mitis, however, all had primary follicles only in the first 2 stages seven days after emergence. All field-collected females of both species were parous, but an earlier flight of nullipars may have been missed. The results indicated that C. carbonarius is autogenous and C. mitis anautogenous, but since they do not agree with observations on these species in other parts of their geographical range, it is suggested that autogeny in species of Chrysops may be facultative, occurring in some areas but not in others according to local conditions and especially the quantities of nutrients accumulated and stored by the insects during the larval stage.