Fleeing from the flies

Published 9:52 pm Tuesday, May 23, 2017

By Susan and Biff Andrews

June 1 is about the time when we abandon the Dismal Swamp for the summer.

Don’t get us wrong, we love the swamp and think it is beautiful year round. There are many wonderful things to see in the summer. But you might pay for the pleasure.

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It’s not the heat. It’s not the mosquitoes. It’s the flies.

A few yellow flies, deer flies or horse flies can be tolerated, but when the price is blood and even the faithful family dog is whimpering and bleeding, it’s time to leave.

All three of these biting flies are members of the Tabanid family. Each is worse than the one before it.

First come the yellow flies in May. They are seven to 10 millimeters in length, yellow-brown in coloration and are active only in daylight hours. The first three hours and the last three hours are when they are most active.

They target people around the head, neck and shoulders. Motion draws them. It’s the females that bite. Males feed on pollen. Females need the protein in blood to produce eggs.

Yellow flies are soon joined by deer flies; same size and habits, but slightly darker in color. They also have stripes on their backs.

Deer flies don’t target the head and shoulders so specifically. They’re equal-opportunity biters and will attack any exposed skin. While their bite is a bit less painful, it will more than likely draw blood.

But it’s the big horseflies, 10 to 25 millimeters, that can inflict serious wounds on people and animals. The mouth of the female contains a “stout stabbing organ with two pairs of sharp cutting blades and a sponge-like part for lapping up the blood.” There is also an anti-coagulant in their saliva that keeps the blood flowing.

Sounds like the description of a monster from a horror movie.

Twenty flies feeding on a cow for 6 hours can suck up to 100cc of blood. And often a cow may have as many as 100 flies on it at a time. Milk cows and cattle may lose up to 100 pounds of body weight a summer due to flies.

Even worse, horse flies can transmit some pretty awful blood-borne diseases.

There is no means of managing the fly population out of doors. In an enclosed space, some livestock folks use a “sticky ball” that is black in color and the size of a beach ball to draw and trap them, but in the open field, there’s little that can be done.

So in spring, we spray up and suffer the yellow flies buzzing around our heads, and the occasional deer fly bite, but we draw the line at horseflies. When we drive into the swamp and hear them hitting the car, it’s time for a U-turn to a friendlier habitat.

Susan and Bradford “Biff” Andrews are retired teachers and master naturalists who have been outdoor people all their lives, exploring and enjoying the woods, swamps, rivers and beaches throughout the region for many years. Email them at b.andrews22@live.com.