Sensilla of the antennae and maxillary palps of Culicoides hollensis and C. melleus (Diptera: Ceratopogonidae).

The types and arrangement of the sensilla on the female antennae and maxillary palps of both sexes of 2 estuarine species of biting midges, Culicoides hollensis (Melander & Brues) and C. melleus (Coquillett), were studied by scanning electron microscopy. Five sensillum types are found on the antennae of both species. Both species have sharp-tipped sensilla trichodea and sensilla basiconica only on subsegments 9-13 and blunt-tipped sensilla trichodea on all subsegments. Sensilla coeloconica occur on subsegment 1 of both species and various other subsegments depending on the species. Sensilla chaetica are found on all subsegments of C. melleus, but only on subsegments 1-8 and 13 on C. hollensis. Both sexes of C. hollensis have either 1 or 2 pits on the 3rd segment of the maxillary palps, which contain 8-15 bulb-shaped sensilla in females compared with 5-6 in males. No pit is found on the maxillary palps of either sex of C. melleus, but rather the bulb-shaped sensilla are distributed individually on this segment, ranging from 13 to 29 on the female and 6-10 on the male palps. These data are compared with data obtained from previously published light and electron microscopical studies of biting midge sensory structures.