Flight of the salt marsh Tabanidae (Diptera), Tabanus nigrovittatus, Chrysops atlanticus and C. fuliginosus: correlation with temperature, light, moisture and wind velocity

The flight activities of Tabanus nigrovittatus Macq. (collected in traps) and Chrysops atlanticus Pechuman and C. fuliginosus Wied. (both collected by hand from man), in North Carolina were measured in the field and correlated with the environmental conditions during the collection periods. The highest numbers of T. nigrovittatus were associated with an intermediate light intensity (40 000 lux), temperatures of about 25 deg C and no wind. C. atlanticus was most active at relatively low light intensity (5000 lux), high temperatures (30 deg C) and air moisture equivalent to 8 mm mercury vapour pressure deficit. The greatest activity of C. fuliginosus was associated with high levels of light (100 000 lux). Graphs are presented for both the actual and predicted levels of flight activity for the significantly correlated values of light, vapour pressure deficit, temperature and wind for each species.