Fresno Westside Mosquito Abatement District

Fresno Westside Mosquito Abatement District uses a number of different traps to capture adult mosquitoes for the determination of abundance and the presence of virus activity.  Most traps are placed overnight in set locations throughout the District and collected the next day for identification and sampling.  Samples are sent to UC Davis where they are tested for West Nile virus, and other mosquito-borne encephalitis viruses.  Additional trapping is typically done in response to virus detection, dead birds, and mosquito activity reported by residents.

The primary traps used by the District include:

1. EVS “CO2” (Attractant: CO2, Targets: Mosquitoes seeking a blood meal)    
2. Gravid Trap “GT”  (Attractant: Organic Matter-Infused Water, Targets:  Egg-laying Mosquitoes)
3. Biogents Sentinel Trap “BG” (Attractant:  CO2, and Sweat Analog Chemical Lure,  Targets:  Mosquitoes seeking a blood meal, specialized for invasive Aedes mosquitoes)
4. Autocidal Gravid Ovitrap “AGO”  (Attractant: Organic Matter-Infused Water, Targets:  Egg-laying Mosquitoes, specialized for invasive Aedes mosquitoes)

Upon collection, mosquito samples are anesthetized, identified to species and sex, and counted under microscope.  Samples of potential disease-carrying mosquitoes are isolated and sent off to University of California, Davis for testing.   Both population totals and the results of virus testing are used to direct future mosquito control operations.

Aedes aegypti, the “yellow fever mosquito”, appeared in the cities of Madera and Clovis in 2013.  This was the first detection of the species in California.  Since then it has spread throughout the Central Valley and Southern California.  It is an aggressive day-biting mosquito that is capable of transmitting Zika and other imported viruses.  Aedes aegypti is a small, black and white mosquito.  The female bites throughout the day and often feeds around the lower extremities.  It will readily enter homes and continue to bite while inside.

Aedes aegypti has been detected in Firebaugh, Mendota, and Tranquility.  Active breeding (multiple generations and life stages) has been detected in Firebaugh in 2017 and Mendota in 2019.  See below for a map of recent Aedes aegypti detections:

STOP Aedes aegypti.pdf

Fresno Westside Mosquito Abatement District utilizes an extensive biological control program, primarily centered around the use of Gambusia affinis,  the ” Western mosquitofish”.  The mosquitofish primarily feeds on aquatic invertebrates and will readily consume mosquito larva of all stages.  FWMAD typically stocks mosquitofish in sustained agricultural (rice, etc.) and domestic (ponds, abandoned pools, etc.) water bodies where there is often a shortage of natural mosquito predators and the fish are able to greatly reduce the number of mosquitoes produced by such sources.

TO REQUEST MOSQUITOFISH FOR YOUR PROPERTY PLEASE CALL 559-659-2437, OR SUBMIT A SERVICE REQUEST

A rice field outside of Dos Palos, CA being planted with mosquitofish