INFLUENCE OF WIND ON HESSIAN FLY (DIPTERA, CECIDOMYIIDAE) FLIGHT AND EGGLAYING BEHAVIOR

The influence of wind velocity on the behavior of ovipositing female H essian flies, Mayetiola destructor (Say), was examined in a wind tunne l. Females exposed to wind speeds ranging from ) to 2.0 m/s, tended to stay for longer on wheat, Triticum aestivum L., plants when the wind speeds experienced were higher, than when they were lower. However, al though flight departing from plants was suppressed at higher wind spee ds, on-plant behavior was not suppressed under these conditions. Thus, females that stayed longer on plants because of higher wind speeds la id more eggs per visit than females at lower wind speeds. Flight direc tion upon leaving a host plant was also influenced by wind. As winds i ncreased > 0.9 m/s, females no longer exhibited flights to upwind grou ps of wheat plants and were more likely to land in downwind groups of plants or to be blown out the end of the wind tunnel. When groups of f emales were released into host plant patches in low (0.1 m/s) or high (0.7 or 1.2 m/s) wind speeds, females in higher winds laid most of the ir eggs in the patches they were released into and in patches downwind patches. In this experiment, the total number of eggs laid during the test period was greater in lower versus higher winds. The effects of the above responses to the reproductive biology of Hessian flies are d iscussed.