Mosquito Control: Licensed To Kill (Part One)
Adulticide On a sultry summer evening, under the spreading light of a streetlamp, two children play a game of hopscotch. So absorbed in their activity are they, completely unmindful of their surroundings, that they do not see or hear the stranger approaching. Slowly but purposefully, the silent killer creeps along, getting ever closer. Something alerts them, the truck engine, perhaps, and the girls look up from their game. The driver of the mosquito control truck has shut off his spray. He smiles and gives the girls a wave, waiting until he is safely past them before switching back on the fine mist that wafts up into the night air, in search of mosquitoes seeking to feed on the children.
This “silent killer” is adulticiding, which sounds a bit strange and mysterious to the layman. If homicide is the act of killing a man, or homid, why not simply call mosquito spraying “mosquitociding? Killing mosquitoes generally falls into two categories: killing adult mosquitoes, or adulticiding, and killing them in the larval stage, or larviciding. Adulticiding can be as simple as swatting a mosquito that has landed on your arm, or as awe-inspiring as a DC-3 roaring down Fort Meyers Beach at 200 feet above the ground with a thick white cloud of pesticide billowing out behind. Until recently, one of the most popular ways of getting pesticide into contact with airborne mosquitoes was through the use of a thermal fog.
Pesticide – most popularly DDT just after World War II, and in later years Malathion – is mixed with diesel oil, heated and released as a cloud of tiny white particles resembling smoke. Many older Floridians have fond memories of riding their bikes behind the DDT truck. They wanted to be coated with pesticide so they could stay out late and play without being bothered by mosquitoes. An appalling practice by today's sensibilities, it doesn't seem to have harmed them in the long run. The latest adulticide technology involves applying an Ultra Low Volume (ULV) spray of undiluted pesticide. This does away with the diesel oil “carrier,” which makes it a good deal more efficient, environmentally friendly, and doesn't cause traffic accidents due to reduced visibility. Tiny droplets, in the size range of 10 – 15 microns (a typical human hair is 100 microns in diameter), are released up into the air, where they spread out to be carried on the evening breeze. Droplets this small tend to remain airborne until they come into contact with a blood-seeking mosquito.
The size is no accident; the equipment is calibrated so that the droplets contain just enough pesticide to kill a mosquito, yet too little to harm larger, non-target insects. Since there is much less wasted pesticide, the amount required is significantly smaller. The machines are quieter and the pesticide plume nearly invisible, resulting in numerous calls to mosquito control organizations from citizens who “haven't seen or heard the truck go by in a long time....”* Adulticiding at the organizational level is accomplished most commonly by truck-mounted spray systems, but also by airplane, helicopter, all-terrain vehicle, and even occasionally airboat. Mosquito control inspectors who respond to domestic service requests are equipped with hand-held sprayers, which they may use for small area space spraying, or to create a barrier around homes surrounded by extensive foliage. The adulticides themselves have also changed over the years.
A common family of pesticides in use today involves formulations of synthesized pyrethrum, a natural insect-killing substance derived from chrysanthemums (ironically one of the first pesticides, dating back to around 400 B.C.) Killing all the mosquitoes isn't possible, however. These flying menaces have been around since the dinosaurs roamed the earth; they have tremendous staying power. Part of the ir strength is their ability to adapt and develop resistance organizations have to rotate their pesticides every few years to prevent this. One tried and true pesticide, often used in aerial applications, is naled. This organophosphate not only disrupts the mosquito's nervous system, it is also caustic in nature, burning the mosquito in addition to poisoning it. A deadly killer of mosquitoes, it's unfortunately also good at eating up application equipment. Every pesticide has its drawbacks. Thus mosquito adulticiding is a balancing act, taking into account a multitude of variables: Protecting the health and welfare of the human population; good environmental stewardship; avoiding pesticide resistance; and budget and manpower constraints.
By and large, spray trucks no longer run on regular routes and schedules. Managers compile data gathered from mosquito traps, service requests, disease surveillance programs and actual observations by mosquito control inspectors to make decisions on what to spray, where to spray, when to spray, and what to spray it from. Mosquitoes are adaptable; but so are the men and women dedicated to keeping them at bay. Additional information on Mosquito Control Go To: www.TuxedoMosquitoControl.com