Yellow flies are members of the deer fly family. They are big biting flies. In the South, they call them yellow flies. Elsewhere they are also known as June flies, stouts, and deer flies. No matter what you call them, their bite is painful, bloody, and almost a way of life.

Scientifically, deer flies are in the genus Chrysops and the family Tabanidae. Yellow Flies are large. That is why the Canadians call them Stouts. They get their name – yellow flies -in the South because they are mostly yellow in color. Many of the deer flies are dark or banded to look somewhat like a mad cross between a bumble bee and a yellow jacket. It does not matter where you are from, if the female yellow fly has ever bitten you, then you understand what a painful pest these flies are.

The Bite of Yellow Flies
The bite from a yellow flies is painful enough to ruin your outdoor adventures. Their mouthparts have sharp, spade-like mandibles which they use to render flesh. It is the females that bite because they need the protein found in warm blood to finish their reproduction cycle.

Producing 50-300 eggs takes a lot of energy. Blood is rich in nutrients and protein. That is why the mouth parts of yellow flies are so effective. As they plunge their mandibles into your flesh, they deposit an anticoagulant. The anticoagulant not only keeps your blood gushing out it also is what causes the bite to hurt so much. Well, not that having spade-like mandibles jabbed into your flesh is pleasant.

The soft parts of their mouths sponge up the upwelling blood quickly and efficiently. They can stab you, drink your blood, and be gone before you can prevent the bite. Don’t worry if your slap missed her. She or one of her many sisters will be back for more. The University of Kentucky estimates that the bite from one deer fly takes about 1-cc of blood from the victim[1]. With about five quarts of blood, humans are a walking buffet for yellow flies.

Resistance is Futile
For centuries we have tried to get rid of biting flies. In places where they thrive, like the South, their infestations are so extreme that they damage livestock production. Ranchers, farmers, and outdoor enthusiasts have tried to control deer flies using pesticides. The result was that few of the flies died and the rest became nearly immune to pesticides. The problem is that deer flies are predatory flies. They do not hunt the dead as blow flies do. They do not need to smell you to find you. While their antennas do track carbon dioxide, they use their eyes as their primary tool for locating prey.

To truly control Yellow flies you have to understand how they hunt and then use that information against them. That is what the Fly Cage does. It mimics the movement of big game animals such as deer, elk, moose and livestock such as cattle, horses, and goats. If you think about how these animals move – at a slow stationary gate as they graze – then you understand the methodology for successfully attracting biting flies. Man moves in much the same way. We slowly fix the fence, plow the field, mow the lawn. We are prime targets for biting flies. The Fly Cage attracts yellow flies and then kills them. It uses their hunting behaviors as a weapon to destroy them, and it works.