The Physiology and Histology of the Contact Chemoreceptors of the Blowfly

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Abstract
[longdash] In flies of a number of genera, contact chemoreceptors are located on the legs and labellum. Those on the legs, and aboral labellar surface are thin-walled socketed hairs with two lumina. Those on the oral labellar surface are small sensilla basiconica. The hairs are equipped with three neurons. On the hair tip they are sensitive to chemicals. The hairs may be stimulated by bending, by water, or by sugars, but any hair may be adapted in turn to each type of stimulus. Stimulation of thirsty flies by water may be effected through the sugar receptors. The most effective carbohydrate stimulators are certain pentoses, hexoses, and compound sugars. The lowest threshold value obtained with sucrose for any single hair was 1 x 10-5 [image]. Rejection of unacceptable compounds can be mediated through a single hair. Whether or not a mixture of sugar and repellent applied to a hair elicits acceptance or rejection depends upon the relative concentrations of the two components. Interpseudotrachial papillae are sensitive to stimulation by unacceptable compounds.