The middle of the summer seems to heighten the deer fly and yellow fly activities in our area. From time to time we get inquiries as to when the county is going to be spraying for them.
First, Robeson County, like most counties in North Carolina not on the coast, has no vector control program. So this means there is no spraying for mosquitoes or other bothersome insects. But the nature of spraying has really changed over the years, anyway. The municipal areas that do spray are really only dealing with the nuisance mosquitoes rather than the ones that transmit diseases. This newer threat tends to live in the backyard — in containers, bird baths and the like — thus spraying from a truck has no measurable effect on them. It would take house-to-house spraying, which is not going to occur at this time.
But back to the biting flies. There is very little distinction between the deer fly and the yellow fly and I think it is safe to say that most of us clump them together as that expletive-deleted fly when they bite. Like mosquitoes (among other species), only the female bites. It needs a blood meal in order to lay eggs while the male is consigned to feeding on pollen and nectar. They are found around bodies of water where they lay their eggs. They prefer to feed for a couple of hours after sunrise and for a few hours before sunset. They do not like open sunny areas so cutting brush back is one way to reduce their impact. They will fly a couple miles for a meal so you certainly do not have to be at the water’s edge.
Not only are the bites painful but they can be itchy and cause swelling in some cases. Livestock are particularly vulnerable and some places have used traps to reduce the infestation. The take-home message is that there is really no adequate means for managing the population of these flies. They are attracted to dark colors, moving objects and carbon dioxide releases. It is recommended that long-sleeve shirts and pants be worn along with using a repellent containing DEET or similar chemical when around them. Spraying is not effective and you run the risk of endangering the other water inhabitants.
On a positive note, if you want to go a la natural, you could encourage their natural predators to hang around: nest building wasps and hornets, dragon flies, cattle egrets, killdeer, frogs and toads. If you are not into the Noah’s arc way of life, temporary relief can be found for a very limited area using sevin, permanone or Malathion.
Bill Smith is director of the Robeson County Department of Health.