Observation on the laboratory life history of Chrysops atlanticus, C. univittatus and C. vittatus (Diptera: Tabanidae)

Data for all life stages of C. atlanticus, C. univittatus and C. vittatus is reported, with the exception of time of development of eggs of C. vittatus. A variation in the previously cited methods of rearing Chrysops larvae is also described. A female of C. atlanticus that had fed on a human host deposited eggs on the side of a laboratory cage 5 days later. The eggs hatched after 8 days. 10 larvae were placed in each of 6 snap-cap vials containing river sand. Tap water was added to the vials and the sand sloped to provide a gradient from moist to complete submergence. Vials were maintained at room temperature (18-26°C). Washed nematodes Panagrellus redivivus were added as food; after 28 days these were supplemented with Drosophila larvae which were used exclusively after 35 days. Vials were checked at 2-5 day intervals by washing the sand and counting the larvae. Numbers of larvae steadily decreased without a trace for the first 12 days, at which time the remaining larvae were divided into 3 additional vials. After 17 days the 60 original larvae in 6 vials were 15 in 15 vials. Of these, 5 were lost in the washing process and 4 died. The remaining 6 larvae pupated after 240, 245, 256, 279, 280 and 336 days. 2 pupae died; 4 pupae produced 3 males and one female after 10 days. Similar data are provided for C. univittatus and C. vittatus, which were reared in the same way. Early loss of larvae in each of the 3 species is attributed to cannibalism. The cause of death of C. atlanticus and C. vittatus is unknown.