Use of spray to battle mosquitoes has little reward for cost, effort

By Bill Smith - Contributing columnist

Several inquiries have been received as to when the county will be spraying for mosquitoes this year. As everyone knows who lives outside of a town with a significant population, there is no spraying that has been done in the past nor will there be in the future. Simply put, Robeson County does not have a vector (mosquito) control program; not having one is the norm in North Carolina.

Most of us recall the “old-timey” fogging truck going up and down a street at dusk. There are 3,500 species of mosquitoes. The mosquitoes that this type of spraying worked on are known as nuisance mosquitoes. These are also the ones associated with flood water and marshes. They rarely carry any diseases and are generally not considered a public health threat. This type of control measure could provide limited protection at gatherings such as ball games.

So the fogging method is designed for the wrong species of mosquitoes, but what about the method of delivery? Imagine you live outside the city limits and a fogging truck comes down your road, goes to the intersection and travels a mile or so and then turns at an intersection on a road parallel to your road — essentially a mile away from the backside of your home. The chemical may travel 300 yards depending on winds — the mosquito can stay safely in between the two sprayings. Of course, if you buddy up to a swamp there may be no parallel road to spray from anyway. This is a complete waste of time.

Our dangerous mosquitoes are the aedes albopictus (the Asian tiger mosquito) and the aedes aegypti. The latter one is responsible for carrying the exotic viruses: Zika, chickagunya, dengue and yellow fever. It has not been found locally — its habitat remains south Florida and Texas. The Asian tiger mosquito can transmit the encephalitis viruses of EEE, St. Louis and LaCrosse as well as dengue to a lesser degree. Both of these are day feeders and work out of back yards in pots, baths, etc. — in fact an inverted soda cap contains enough water to meet their needs. They travel very short distances. To reiterate my point, a truck fogging in the evening is missing these mosquitoes’ habitat and when they are active. Oh yeah, the albopictus has built up a tolerance for most of the chemicals used in fogging so they would not work even if they came in contact with the control measure. Personal protection, such as mosquito spray and long sleeves, and removing sources of pooling water around the house are the best defenses.

Some years ago, the Lumberton Airport was used for aircraft to do aerial spraying for the coastal counties after a particular storm. Robeson County was not approved for spraying. After seeing the airplanes fly overhead for several days on their way to the coast, I received several comments on how effective they had been in the eastern part of the county at knocking out the mosquitoes. So much so, that the western half wanted to know when it would be their turn. I asked the pilot one day to bank toward the west a distance and wiggle his wings. Amazingly the mosquito population was markedly reduced.

The take-home message is that neither got sprayed, but as the adage goes, one’s perception is one’s reality.

By Bill Smith

Contributing columnist

Bill Smith is the director of the Robeson County Health Department.

Bill Smith is the director of the Robeson County Health Department.