Swarms of flies concern nearby residents

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.    

Over the past couple of weeks several people have submitted some weird flies that were swarming in large masses near their homes. These flies are known as March flies in southern states because they their form large mating swarms during the month of March. They normally swarm in May in Michigan. They are also known as love bugs because they often fly around in tandem. Bug geeks call them bibionids (Diptera: Bibionidae). The flies are odd looking with large hairy eyes. Like other primitive flies in the suborder Nematocera, they have seven or more “freely articulated” antennae segments. The flies do not bite and are harmless.

Female March flies dig burrows in the soil and deposit a mass of 200 to 300 eggs, then die soon after. The larvae are primarily scavengers and feed on decaying organic matter. Adults are attracted to flowers when they are not swarming for mates.

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