The reproductive life history and blood meal sources of Chrysops hirsuticallus (Diptera: Tabanidae)

The reproductive life-history and sources of blood-meals of Chrysops hirsuticallus Philip from Mendocino County, California, were determined in 1971-74. Nulliparous females predominated in late April and most of May, whereas uniparous and biparous ones constituted the greater part of the collections made in late May and June; triparous females were recorded for the 1st time for this species in the field. Egg retention increased with advancing gonotrophic age. Vegetation sweeps yielded comparable proportions of females with their terminal ovarian follicles in development stages up to II (55%) and in stages III-V (45%). Over 80% of those caught by hand while attacking man were in stage II, and only 2% in stages III-V. Females reared from pupae and surviving for at least 8 days without a blood-meal entered ovarian diapause on the 4th day, indicating that C. hirsuticallus was anautogenous in the study area. The spermathecae of 17 host-seeking nulliparous females that were dissected contained spermatozoa, which indicated that mating preceded blood-feeding. Serological analysis of 19 engorged females showed that cattle and Columbian black-tailed deer (Odocoileus hemionus columbianus) were frequent hosts, and that limited feeding also took place on smaller mammals (Lepus californicus, Didelphis virginiana and Procyon lotor).