EXPERIMENTAL COMPONENT ANALYSIS OF THE FEEDING RATE OF THE BLOWFLY PHORMIA REGINA (DIPTERA: CALLIPHORIDAE)

Abstract The feeding rate of Phormia regina is constant over the whole feeding period, contra-pressure of the crop contents having no effect. The mechanism by which contra-pressure effects are negated involves the function of two previously undescribed structures in the crop and crop duct. These structures, described in the text, act as valves and a pump. An alternative mechanism, by which contra-pressure effects could be negated in insects lacking these structures, is discussed. The physical effects of variation in the feeding position of the labellum, in response to changes in the physical nature of the substrate, are discussed in relation to the feeding rate. The feeding rate is shown to be higher on semi-liquid substrates.