The mouth-parts of the Down-looker fly, Rhagio (=Leptis) scolopacea (L.) Diptera, Rhagionidae)



A detailed account is given of the anatomy of the mouth-parts of Rhagio scolopacea (L.) (Rhagionidae) and some comparisons made with earlier studies of Scopeuma stercoraria (L.) (Cordyluridae) and Empis livida (L.) (Empididae). The probable movements and functions of the mouth-parts are deduced and the morphological adaptations to these discussed and compared in a similar manner. Rhagio shows no predatory adaptations and is possibly a nectar feeder. Homologies are traced including that of the maxilla and a general discussion on homology, with special relation to particular problems in these three species, is included.