How do taste receptors on a blowfly’s legs help start feeding?

For the blowfly (Phormia regina), feeding behavior is initiated when food stimuli come into contact with specialized taste organs located on the tarsi—the terminal sections of the legs—as well as the proboscis.1

These taste receptors, housed within hairlike structures called sensilla, function as the primary trigger for the insect's sucking response. When the fly walks on a surface, the taste receptors on the ventral surfaces of the tarsi detect food-related chemicals, such as sugars. Once these receptors are stimulated, they send signals directly to the central nervous system, which elicits the sucking reflex.12

The feeding process continues until the signals from these receptors decrease due to adaptation, or until the threshold for the sucking response is raised by internal signals from distension receptors in the foregut, which indicate that the fly is satiated.1