The fly Palpada mexicana is one of the many syrphids that employ hilltopping as a mating system. In central Arizona, males of P. mexicana can be found on peaktops in spring and, to a lesser extent, autumn. Year after year, the flies gather to perch or hover near certain prominent plants on the ridgeline that constitutes Usery Peak, Maricopa County. About 20% of all marked males returned on subsequent days to the landmarks where they had been captured. Although site fidelity and territoriality are apparently fairly weak in this species, the behavior of P. mexicana is similar to that of various hilltopping flies and other insects, but markedly different from those syrphids that wait or search for mates at flowers or oviposition sites.