The Town of Windsor’s Environmental Mosquito Management Program
The Town of Windsor Mosquito Management Program completed its 10th year of cost effective biorational integrated mosquito management operations in 2010 with Colorado Mosquito Control as its contractor. Mosquitoes are dynamic insects which are capable of rapid populations increases dependent on habitat, water level, rainfall events, and temperature patterns. The experience and knowledge possessed by CMC employees for the local land and irrigation patterns, enables an overall reduction of mosquitoes. The biorational management operations and data driven response to spikes in mosquito abundance are aimed at reducing the risk and annoyances associated with mosquitoes. If left unmanaged residents residing throughout large sections of the town would be burdened by mosquitoes, thereby resulting in a decreased quality of life and reduced ability to enjoy outdoor activities.
The objective for the Town of Windsor Mosquito Management Program is to utilize trained field biologists to suppress the number of mosquitoes, in the aquatic larval habitats. This reduces the potential for mosquitoes to emerge from the water to feed on and reduce the transmission of vector borne diseases to the residents of Windsor. The Town of Windsor monitors adult mosquito populations via a surveillance trapping network to enable a proactive response to suppress West Nile Virus vector mosquito populations prior to a public health emergency outbreak. Adult mosquito population data provides real time information regarding the nuisance and risks associated with mosquito populations in Windsor. Trapping data provides a scientific basis when determining the need to reduce the mosquito populations via adult mosquito control materials. CMC sets 10 mosquito surveillance traps in the Town of Windsor on a weekly basis to monitor the mosquito counts within town.
This objective enables a decline in the overall mosquito populations, while reducing the threat of mosquito borne disease transmission, at the least possible cost, and with the least possible impact on the people and natural environment. CMC will continue to strive and demonstrate a commitment to Integrated Pest Management principles for a progressive approach to mosquito reduction.
The larval control area for the Town of Windsor encompasses approximately 32 square miles within and surrounding the town limits of Windsor. Although many of the mosquito production sites are outside the town limits, all are well within the flight range of most mosquitoes. Larval control work outside the town will continue to remain a critical part of the overall operations of CMC.
Studies have indicated that adult mosquitoes can travel several miles in search of a blood meal and new habitats for offspring. Mosquitoes can be attracted from outside town limits into a more favorable environment inside town limits by factors including carbon dioxide, protection from wind, a nutrient rich larval site and harborage from heat. Mosquito reduction by Colorado Mosquito Control across the cities within Larimer and Weld Counties greatly reduces transient mosquito populations, thereby protecting the public from West Nile Virus transmission and the nuisance associated with mosquitoes.
How Is The Mosquito Management Program Funded?
The Town of Windsor Mosquito Management Program is funded by town residents through the town’s storm water drainage program. If you refer to your storm water bill, there is a charge of $1/month or $12/year paid by each lot in the limits of Windsor. The $12/year per lot funds the surveillance monitoring of larval mosquitoes in the water, the application of bio-larvicide control products, the monitoring of adult mosquito populations via mosquito traps throughout the town, and data driven response & control of adult mosquitoes through ULV fogging applications. The money collected from the storm water drainage program also funds all Windsor resident requests for CMC technicians to inspect resident properties and to provide fish for control of mosquitoes in ornamental ponds, where applicable.
The History behind the Mosquito Management Program
Windsor’s Integrated Mosquito Management program focuses on utilizing naturally occurring soil bacteria, larvicides, to control mosquitoes in the larval stage, instead of relying entirely on application of pesticides in the form of fogging materials. The program primarily utilizes applications of Bti, a stomach toxin, which is target-specific to larval mosquitoes. This naturally occurring bacteria is activated by a specific pH within the larval gut and disrupts the larvae’s ability to consume and digest food resources.
When properly carried out, by trained applicators, IPM programs return beneficial results in reduced pesticide use, reduced frequency of pesticide resistance, and reduced exposure to pesticides by the environment. The Mosquito Management Program offered by CMC follows successful IPM principles for cost effective, scientific methods of survey/inspection, evaluation, diagnosis, application and record keeping of materials used.
The 2010 Windsor Mosquito Management staff consisted of 5 Full-time Equivalent employees (FTE). Specifically, we had 1 Manager, 3 Field Technicians, .5 Surveillance Technician and .5 Office Staff personnel. To date 309 larval mosquito habitats are included in the regular inspection and larviciding program for the Town of Windsor Mosquito Management Program. There were 12 new larval sites identified and added to the routine inspection program in 2010. Field technicians methodically inspect larval habitats twice a week, weekly, bi-weekly or post rainfall, as deemed necessary based off of historical data. A technician may spend the day inspecting a variety of habitats ranging from urban mosquito breeding locations (storm drains, catch basins, wading pools, paddle boats & tire piles), as well as cattail marshes, stagnant ditches, reservoir edges and irrigated pastures. Inspections are performed to determine whether larval mosquitoes are present or not at a site. Once the presence of mosquito larvae is confirmed, larvicides are applied. This enables targeted control, while reducing the miles of city streets that need to be fogged for adult mosquitoes.
2010 Surveillance Light Trap Data Comparison
In 2010, an average of 11 surveillance light trap locations monitored adult mosquito populations within Windsor. CDC battery-operated “light traps” were set weekly in each location to provide adult mosquito population data for seasonal comparison. The Town of Windsor added two new surveillance locations to the Mosquito Management Program in 2010. A surveillance location was established in the Steeplechase subdivision (WR-16) to monitor mosquito populations in the Steeplechase, Belmont Ridge, and High Pointe communities. A second location was established in the North Shores community (WR-15) to monitor mosquito populations in the Ventana, North Shores, and Windsor Estates communities. CMC also expanded surveillance monitoring in the Water Valley/ Pelican Lakes communities through a cooperative effort between Windsor, Pelican Lakes Golf Course and Water Valley. CMC established locations in Water Valley North (WR-17) and Water Valley South (WR-18) to monitor mosquito abundance within the residential communities.
There were 134 surveillance traps set in 2010 which collected a total of 31,922 mosquitoes from within the Town of Windsor. The average number of mosquitoes caught per trap per night was 238 and the average Culex spp. mosquitoes caught per trap per night was 74. The composition of mosquitoes trapped was 30.6% (9,772) Culex tarsalis, .4% (135) Culex pipiens, 68.7% (21,927) Aedes/ Ochlerotatus spp., and .3% (82) Culiseta spp. mosquitoes.
Targeted Ultra-low Volume Adult Mosquito Control
Adult mosquitoes can come from unknown unidentified sites or may migrate in from uncontrolled areas. Windsor uses all available data from CDC light traps, Mosquito Hotline annoyance calls, and field technician reports to focus adult mosquito control efforts on specific, very limited “targeted” areas. In parts of the community were high numbers of mosquito annoyance calls are received, “floater” CDC light traps are set to evaluate adult population levels and species make-up. In most cases, a direct correlation is evident between areas with high complaint calls and high trap counts. While this correlation allows us to focus adult control in these areas, the emphasis is placed on finding the source of breeding and continued larval control measures.
Over 95% of the Windsor’s Mosquito Control Program is targeted against larval (aquatic stage) mosquitoes utilizing biological control materials. However, on occasion adult mosquito spraying becomes necessary. At that point Colorado Mosquito Control utilizes 3.3% Permethrin in ultra low volume (ULV) spray applications via truck mounted fogging machines. ULV sprayers dispense an extremely small amount (0.0035 pounds per acre) of fine aerosol droplets which stay aloft and kill adult mosquitoes on contact.
Permethrin is a synthetic pyrethroid similar to the insecticide pyrethrum which occurs naturally in chrysanthemum plants. Permethrin is found in a variety of products, including household insecticides, flea dips, repellents for clothing, sprays for pets, and lice shampoos. This pesticide has been selected to achieve effective control of mosquitoes and suppression of West Nile Virus transmission with the least impact on human health and the environment.
Fogging applications are performed based on mosquito populations caught in traps on a nightly basis. The town is divided into zones. Specific neighborhoods are fogged when surveillance traps catch 100 floodwater mosquitoes, referred to as a “Nuisance Threshold” or 50 Culex mosquitoes, referred to as a “Disease Threshold”. The thresholds for fogging applications are established by an industry standard that measures vector and nuisance mosquito populations.
Colorado Mosquito Control uses state of the art technology, correct application timing, and least-toxic products to minimize non-target impacts. All adult mosquito control is accomplished using calibrated Ultra Low Volume (ULV) equipment and performed after dusk. This type of equipment produces droplets averaging 12 microns in diameter and allows for a minimal amount of product to be put into the environment. These treatments take place in the evening when mosquitoes are flying in greater numbers and non-target activity is greatly reduced. Using this application technique, the overall goal of minimal environmental impact and effective adult control is achieved in the targeted area.