Gustatory hairs on the mosquito, Culiseta inornata

Gustatory hairs were investigated on the legs and mouthparts of Culiseta inornata (Williston) (Diptera: Culicidae). One type of hair, each innervated by four neurons, was found on the legs. Two of the neurons responded to NaCl stimulation, one neuron to water stimulation, and one neuron to sucrose stimulation. Three kinds of hairs designated Type I (T1), Type 2 (T2) and Type 3 (T3) were analyzed on the labella. The T1 hairs are innervated by one sugar neuron, one mechanoreceptor, two salt neurons and one water neuron. The T2 hairs are innervated by two salt neurons and one mechanoreceptor. The T3 hairs, located on the oral surface of the labella, are innervated by a variable number (2-5) of neurons. Precise identification of the T3 chemosensory neurons was not made because of the small size and inaccessibility of the T3 hairs. Chemosensory hairs on the tip of the labrum were tested electrophysiologically. the sequence of decreasing effeectiveness for the three salts tested was KCl greater than NaCl greater than LiCl. Labral chemoreceptors also responded positively to sucrose.