The interaction of sensory activities from internal stretch receptors and from external sugar receptors was studied in relation to proboscis extension and sucrose intake of the blowfly. The tarsal threshold for proboscis extension was elevated in flies after the recurrent nerve was cut. Cutting either the recurrent nerve or the ventral nerve cord did not alter the labellar thresholds for proboscis extension but did influence sucrose intake by prolonging the duration of intake. After the ventral nerve cord was cut, the flies did not stop ingestion as long as sugar receptors in the interpseudotracheal papillae were stimulated. Tonic impulse discharges from the intact recurrent nerve were divided into efferent and afferent types. Efferent impulses from the brain were thought to be transmitted to the hypocerebral ganglion-corpus cardiacum complex for regulation of opening and closing of the foregut valves, of peristaltic movements in the foregut. Afferent impulses were thought to be discharged from the foregut stretch receptors which detected peristaltic movements in the foregut.