Deer Fly



There are many different species of deer flies, in the genus Chrysops, in North America, most are small and yellow and have a painful bite.


The deer fly Chrysops lateralis above is a typical deer fly in that it is small and yellow with dark coloration on otherwise clear wings. The thorax is striped and the abdomen is yellow with black bands.


Chrysops dimmocki female


The larvae breed in moist habitats such as in mud along the edge of streams or ponds. Adults emerge during the summer and females begin to bite humans, horses, dogs, deer and other mammals in their search for blood. Males do not bite and are found on flowers where they collect pollen.

Females use their sharp mouth parts like a sissors to stick and cut through the skin or hide of their hosts. This creates sharp pain and a pool of blood. The fly then injects saliva into the wound and sponges up the blood before it coagulates.


It is difficult to avoid these flies during the summer when they are searching for hosts. You can purchase a cap with a sticky pad at the rear that will catch flies heading for the back of your head to bite.

As deer flies bite deeper into flesh, small hooks on their mandibles help them anchor into their host. As they create a pool of blood to sponge up, they are more vulnerable to being swatted and killed. Waving hands in the air will only temporarily deter these flies that have already selected you as a host.

There are passive traps that can be installed along the perimeter of deer fly breeding areas which are dark in color and supported on stilt legs. Flies are attracted to the outline and dark shape and can be collected from these traps in large numbers. It is little comfort to know that these traps only lessen the numbers that attack not the certainty of the attack itself.

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