Deer Fly

The bites of female deer flies are more painful than mosquitoes as they use their razor-like jaws to tear and slice flesh apart. They are even able to bite through clothing. The flies will pour clot-preventing saliva into the open wound and then suck the blood for several minutes. If not treated quickly, the bites may cause large swellings or lesions, become itchy, and cause a high fever.

Suitable habitats include salt marshes, swamps, bogs, and areas along the edges of ponds, lakes, and streams. Deer fly larvae will feed on organic debris, insects, small crustaceans, snails, earthworms, and other organisms.

Deer flies can transmit equine infectious anemia virus and anthrax among cattle and sheep. They are the most common cause of tularemia between rabbits and humans in the Western US. They are suspected of transmitting Lyme disease as well. Large numbers of deer flies can cause an animal to lose up to 300 ml of blood in a single day and can severely weaken or even kill them.