UC Riverside

House flies (Musca domestica L.) are common synanthropic pest associated with confined animal operations and are known carriers of many disease-causing pathogens affecting humans and animals. House fly production remains a significant problem for producers. Reducing the number of house flies dispersing away from a development site may impact both pathogen transmission and nuisance to humans and animals near fly development sites. This dissertation investigates the flight behaviors of the house fly under field conditions in southern California which may be used in future fly management programs. In chapter 1, a study was conducted to investigate the diel flight activity of house flies on two different active dairies in southern California. Collection period (time of day) was a useful predictor of house fly activity, as time is essentially a proxy for diel changes in temperature, humidity, light intensity, and even wind speed in southern California. Male flight activity peaked before females. Temperature, light intensity, and wind speed had a significant effect on activity throughout the day. In chapter 2, the flying height of house flies was examined using vertical 2.13m-tall sticky traps. House flies were evenly distributed over this trap height, except for flies captured on traps positioned in or near the edge of an alfalfa field. Temperature, relative humidity, and wind speed were linearly associated with changes in flying height. The even distribution of house flies over the traps indicate house flies are almost certainly flying above top of the traps. In chapter 3, the relationship of house fly flight direction with environmental variables was investigated, using a release-recapture study. House flies are not dispersing randomly, and the short-range flight of male and female flies was toward the southeast. Flight direction was significantly correlated with time of release, solar position, wind speed, and temperature. Dispersing flies may have been using a nearby tree line as a visual cue thus flying in this direction. Chapter 4 investigated the impact a visual target would have on the direction of flight for house flies. The mean direction of flight was altered by the target but did not result in a significant shift in flight direction towards the target. More house flies captured when the target was raised and the aspect of the target facing the release point was sunward (reflecting sunlight). Overall, house fly flight behaviors are complex, and are likely impacted by all observed environmental variables. Changes in temperature and sunlight (time of day) had a wide-ranging impact on house fly flight behavior, affecting flight activity and directionality. It is anticipated that as sampling techniques become more refined the impact of weather on house fly flight behavior will become better characterized, but continued research is necessary.