Deer Fly

G. sp.

A Tabanid Fly, photo © by Mike Plagens

This fly was photographed mid-air as it hovered about 1 meter above the ground over and open dirt pathway. Reynold's Canyon, Sierra Ancha, Gila County, Arizona, USA. June 2011.

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Once the naturalist accepts the fact that these insects are often looking for a blood meal and that a hiker represents a possible victim, these amazing creatures will be seen as both colorful and quite fascinating. It turns out that only adult female deer and horse flies are the least bit interested in human blood. Males, like the one shown here, forgo blood feeding altogether, so as to devote full time to finding and defending access to females. The immature stages of deer flies are likewise harmless to people. They feed in mucky soil as might appear at the margins of a perennial stream or about a desert spring. Because this food is rather low in proteins, the females use blood as a nutritional supplement.

In my experience, deer flies are rarely abundant in Arizona's sycamore canyons and their usually attack spot are the ankles or calves. Thus their biting tactic can sometimes proceed without the hikers knowing. In some cases these flies may be a vector for tularemia, a bacterial disease of primarily rabbits.

Tabanidae -- Deer and Horse Fly Family

More Information:

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Arizona Naturalist
Sycamore Canyons
Invertebrates in Arizona's Sycamore Canyons


Copyright Michael J. Plagens, 1999-2011