Comparative Flight Dynamics of Knapweed Gall Flies <i>Urophora quadrifasciata</i> and <i>U. affinis</i> (Diptera: Tephritidae)


  • Bernard D. Roitberg Centre for Pest Management Department of Biological Sciences Simon Fraser University Burnaby, BC V5A 1S6


By using laboratory flight mills, I tested the hypothesis that the differential distributions of knapweed gall flies, Urophora quadrifasciata and U. affinis, among knapweed sites can be predicted by the flight propensity and endurance of the flies. Results from tests did not support the prediction that the former species displays the greater propensity for flight and endurance. I discuss several reasons supporting the values obtained and their validity for use in interspecific comparisons. Finally, I point to the danger of extrapolating laboratory behaviour to the field.