Overview

Two major categories are known: olfactory sensilla and gustatory sensilla. Chemosensilla typically consist of seta, socket, neurons, thecogen, scolopale, the inner trichogen and the outer tormogen or auxiliary cells.

Olfactosensilla

Two major types occur: the single walled sensilla, the sensilla basiconicum, and the double walled sensilla, the sensilla coeliconium.
The pores are plugged (plugged pores) with a cap-like structure. These pores are filled with an unknown material believed to be continuous with a film over the sensilla surface.

Gustatory Sensilla

These may occur setiform, usually with a single pore at the tip, or associated with cuticular pores. An example is found in the sensilla on the tip of palpal article IV. Setiform gustatory sensilla also occur on other locations, e.g., Haller's organ. Many are multifunctional sensilla, e.g. both mechanosensory and gustatory in function.