Deer flies (genus Chrysops) are very pesky flies of not only humans, but also other mammals such as cattle, horses, dogs, etc. They are very similar to Horse flies, which share the same family (Tabanidae). They have distinctive, large eyes that are patterned with gold or green, and dark bands across their wings. The females bite, in search of a blood meal, whereas the males feed on pollen. The bite of the female is often quite painful (not unlike a bee sting for many people), and many people react to the fly’s saliva, causing pain and itching at the site of the bite. Significant allergic reactions can develop for some people.
The flies are abundant in damp, wooded or wetland environments, due to the fact that their larvae are aquatic, feeding on small insects and pupating in the mud at the edge of the water. Natural predators of deer flies include frogs, toads, spiders, wasps and hornets, dragonflies, and birds such as the killdeer.
Additional Information and Photos:
- Horse Flies and Deer Flies (University of Kentucky)
- Pest Flies of Pastured Cattle and Horses (Cornell)