Notes on the Biting Response of Tsetse Flies

SummaryThe physiology of the biting responses of three species of tsetse flies was investigated. Specimens of Glossina palpalis, G. morsitans, and G. brevipalpis were attached by the wings to wax-tipped applicator sticks and subjected individually to a variety of stimuli. Their reactions were compared to those of free flying caged flies. Behavioral components of the normal biting response include characteristic movements of the mouthparts, salivation and defecation. Heat is the prime stimulus to feeding although contact of the feet with a substrate may alone elicit a low level of response provided the substrate is neither too smooth nor otherwise repellent. The antennae are the principal site of thermoreceptors mediating the feeding response. Neither odor nor chemicals in contact with the tarsi are effective stimuli. Responsiveness increases as the fly becomes more hungry, but as the final stages of starvation approach the fly becomes refractory. The repellent 622 prevents the feeding of caged free flying tsetses; however, attached flies will feed through this compound. 622 appears to act as an olfactory repellent.