Functionality of a reduced proboscis: Fluid uptake by phigalia strigataria (Minot) (Geometridae: Ennominae)

Abstract

The structure and functionality of the reduced proboscis of males of P. strigataria was studied. Scanning electron microscopy revealed a proboscis structurally similar to functional proboscises of other lepidopteran species, including chemo- and mechanosensilla and a tip-region with larger spaces between the dorsal legulae. Drops of red food coloring applied to the dorsal legulae entered the proboscis. Subsequent dissections exposed a complete and functional gut containing food coloring. We suggest that Lepidoptera with reduced proboscises might rely on capillarity as an initial step for fluid to enter the proboscis for subsequent uptake. Field observations are needed to determine if P. strigataria, and other Lepidoptera with reduced proboscises, feed in their natural habitats.