Do Nearctic hover flies (Diptera: Syrphidae) engage in long?distance migration? An assessment of evidence and mechanisms

Long-distance insect migration is poorly understood despite its tremendous ecological and economic importance. As a group, Nearctic hover flies (Diptera: Syrphidae: Syrphinae), which are crucial pollinators as adults biological control agents larvae, almost entirely unrecognized migratory examples of highly behavior among several Palearctic species. Here, we examined evidence mechanisms for four fly species (Allograpta obliqua, Eupeodes americanus, Syrphus rectus, ribesii) common throughout eastern North America using stable hydrogen isotope (?2H) measurements chitinous tissue, morphological assessments, abundance estimations, cold-tolerance assays. Although further studies needed, nonlocal isotopic values obtained from specimens collected in central Illinois support the existence long-distance fall Eu. to lesser extent S. ribesii rectus. Elevated americanus during expected autumn period supports such behavior. Moreover, high phenotypic plasticity morphology associated with dispersal coupled significant differences between local suggest that exhibits unique suite traits decrease costs flight. Finally, compared ostensibly nonmigratory A. was less cold tolerant, factor may be Collectively, our findings imply occurs flies, but consider methodological limitations study addition potential consequences these novel findings.