Different species are found in different habitats. Adults of some species are found exclusively along hedge rows and edges of woods or in the forests. Other species prefer more open areas with sparse vegetation such as old fields. Adult deer flies are present from early Spring to late Fall but each species has its own period. Adult deer flies are swift, strong fliers and may fly more than a mile from their breeding areas.
Most deer flies require a blood meal to develop eggs.
However, they also feed on pollen, nectar and perhaps insect excreta, honeydew. Eggs of most deer flies are placed on vegetation in moist areas. Most of the immatures or larvae are found in water or wetlands and are predacious on other organisms or eat vegetable matter. They also have their own natural enemies such as dragonflies, wasp, spiders and birds. Featured Creatures publication on these flies.