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V. Adulticide

Adulticiding is the term used to describe the process of applying insecticides to kill the flying adult mosquito. Adulticide treatments are performed by the use of 14 truck mounted ultra low volume (ULV) ground aerosol sprayers, two sprayers mounted on all terrain cycles, and two fixed-wing twin-engine aircraft equipped with ULV aerosol sprayers. Adulticide treatments are primarily performed at night because most mosquitoes are active after dusk. Also, during the summer, the air is more stable at night with less wind and less thermal uplifting caused by heating from the sun. Droplet size of the spray particles range from 13-15 microns in diameter for the ground applications and 20-25 microns in diameter for the aerial applications. The concept for the applications is to have small spray particles suspended in the air long enough for them to effectively impinge on the flying adult mosquitoes. All adulticide treatments are performed after the analysis of mosquito and arbovirus surveillance data, and only when they are needed to reduce nuisance levels or for mosquito borne disease prevention. It is costly and an unwise practice to spray in an area that does not justify a treatment, based upon thresholds established by the District's analysis of information. All products used for adulticiding are registered and approved by the EPA and when used according to labeled directions, do not pose any unreasonable risk to the environment or human health.

Ground ULV Adulticide

Truck mounted ground ULV sprayers are designed for use on public roads and commonly seen spraying at night. Each sprayer is carefully calibrated to apply the appropriate amount of material according to labeled directions. Calibration checks are made routinely, along with droplet size readings, in order to ensure efficiency. Trucks spray public roads with speed limits of 20 mph or less, and operate at either 15 or 20 mph depending on location. A chemical called resmethrin, under the trade name Scourge, is used in all ground ULV adulticide applications. Resmethrin is a synthetic pyrethroid very similar to pyrethrum, a natural insecticide obtained from the chrysanthemum plant. It is applied at a rate of 0.0026 pounds active ingredient per acre. Even though this is an extremely small amount to apply, many particles can be aerosolized into the air to effectively control flying adult mosquitoes.

Sprayers mounted on all terrain cycles are used for off-the-road and special applications inaccessible to the standard truck-mounted sprayers. Woodland locations close to residential communities are commonly sprayed with these units.

Aerial ULV Adulticide

Aerial ULV adulticide applications are performed by the use of a twin engine Britten-Norman Islander aircraft and a twin engine Piper Aztec aircraft. Applications are initiated at dusk and conclude 3-4 hours after dusk. The aircraft operate at an altitude of 200 feet at a speed of 140-150 mph. All spray operations are approved by the Federal Aviation Administration (FAA). The crew consists of a FAA qualified pilot and co-pilot. For extra safety measures, the co-pilot is equipped with night vision goggles. Each aircraft is equipped with a GPS guidance system that the crew uses for following a predetermined flight path and spray grid. An onboard weather station keeps the pilot informed to actual wind speed and direction at the point of spraying and will make flight adjustments when necessary. Applications are calibrated and performed with a swath width of 1,000 feet. The margin of error is three feet using the GPS system. A flight recorder is also on board to graphically record the spray mission so it can be overlaid on a map. The chemical naled, under the trade name Dibrom, is used for these applications. Naled is sprayed at a rate of 0.75 ounces per acre, which is the midrange of the labeled rate. Aerial applications are reserved for those mosquito populations which cannot be effectively controlled by the ground ULV treatments. One treatment with one aircraft will cover 10,240 acres.


VI. Public Information

Public information is an ongoing and integral part of the program. It is incumbent upon the District to keep residents informed about how and why we conduct operations. It is also important that residents have an understanding about basic mosquito biology so they can become more aware of mosquito habitats and behavior. In doing so, they are better able to take measures to help reduce mosquito breeding on their property. Effective mosquito abatement involves community involvement. At times of public health concern, the District works to keep residents up to date on the status of a mosquito borne disease threat. These include the measures the District is taking and the measures that residents can take to help reduce mosquito breeding, and better protect themselves from mosquito bites. Some of the ways the District accomplishes its public information program are:


School Presentations and Demonstrations

District personnel regularly make presentations to many of our school children throughout the parish. Presentations include an overview of the program, along with science demonstrations. Field trips to our headquarters are also conducted. Informational brochures, booklets and coloring books are distributed depending on the grade level. A 5-day classroom course in mosquito biology and control directed toward the 7th grade has been developed and is ready to be administered to all 7th grade classes in the public school system. The course, complete with a detailed syllabus, is designed so that each 7th grade science teacher can teach the course to his or her students.

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