Distribution of sensory sensilla throughout the foregut of Chrysops exitans (Diptera: Tabanidae).

Sensilla of the foregut, beginning at the distal-most tip of the labrum and extending proximally through the food canal, epipharynx, and cibarium to the stomodaeum, were examined in n = 18 female specimens of Chrysops exitans Walker. Totals of 328 setiform sensilla (mean = 18.2; ± 1SD = 1.67; range, 14 to 20), and 36 basiconic sensilla (mean = 2.0; ± 1SD = 0) were observed in the food canal of n = 18 individuals in the sample population. Both types of sensilla were significantly aggregated distally in the canal. Five to 10 setiform sensilla were observed in each lateral wall of the epipharynx, and a single median group, consisting of both setiform and basiconic sensilla, was positioned immediately distal to the mouth opening into the cibarium. Additionally, two pairs of basiconic sensilla were consistently observed in the stomodaeum of every fly.