Adult Mosquito Surveillance
Mosquito surveillance monitors local mosquito populations in order to prevent them from reaching nuisance levels and potentially transmitting diseases. The data gathered through the surveillance program is used by our inspectors to maximize control effects while minimizing effort, cost, and environmental impact.
The oldest and simplest method of mosquito surveillance is tracking populations of adult females. Adult females are the focus of this method because they are the only form of mosquito that bites people. Knowledge of current populations when compared to previous months or years reveals information regarding the prevalence of species, the habitat that is producing them, the time of day they are biting, etc.
The New Jersey Light Trap
This trap is the “workhorse” of surveillance. Using the mosquito’s natural attraction to light, this trap uses a 25W bulb to draw in pests. Approaching the light, mosquitoes are forced downward by a powerful fan into a collection cup. There they are exposed to lethal fumes. Mosquito Control places between 20-24 light traps around the County yearly. Sites are chosen to sample mosquito populations from a variety of residential, commercial, and public properties. They provide a good “cross-section” of the places where people and mosquitoes interact. A staff member collects trap samples daily, Monday to Friday (May through October). Our entomologist sorts the samples, identifies the species, and records the data. This data is shared with mosquito inspectors to help them refine their control efforts in relation to current conditions.
While knowing the current status of mosquito populations in the County is important, it only provides a partial picture of the overall mosquito situation. Because mosquitoes are not only bothersome but a threat to your health, it is vital to know if they are carrying any disease causing agents, or pathogens, and what those pathogens are.
The Mosquito Control Division actively monitors established and emerging mosquito borne diseases including West Nile virus, Eastern Equine Encephalitis, Dengue Fever, and Chikungunya in the local mosquito populations weekly (May through October). Samples collected are sent to the NJ Department of Health (NHDOH) laboratory for specialized testing. If pathogens are detected in the samples submitted we know where to focus our efforts and whether additional control measures, like adulticiding, are required.
The CDC Trap
The Centers for Disease Control (CDC) miniature light trap is a portable device that uses dry ice as an attractant. Species of mosquito that bite mammals, including humans, are drawn to the carbon dioxide of the host’s exhalations. The dry ice in this trap simulates an animal’s breath and lures the mosquitoes in for capture. A small fan pushes the mosquitoes into a net where they are kept alive until collection. In the Mosquito Control Division’s laboratory the entomologist groups the mosquitoes by species into tubes that are sent to the NJDOH laboratory for West Nile virus testing.
The Gravid Trap
The Gravid Trap is a portable device that uses a grass-based infusion, commonly called “stinkwater,” as a mosquito attractant. Species of mosquito that lay their eggs directly on or very near foul smelling water are attracted by this device. The trap’s fan pushes the mosquitoes into the collection net where they a kept alive until collection. Our entomologist identifies the species and sends the samples to the NJDOH lab for testing. Mosquitoes collected by this trap more often bite birds than mammals. Because bird populations serve as reservoirs of pathogens like West Nile virus that can be passed to people, it is important to monitor these mosquitoes.
The BGS Trap
The Biogents Sentinel (BGS) trap is a portable mosquito trap designed primarily to sample the Asian tiger mosquito, Aedes albopictus. The strong contrast of the white trap body with the black trap opening is highly attractive to this invasive species. Additionally, a chemical lure that simulates human body odors is placed in the trap. The combination of these features brings the mosquitoes near the trap fan’s downforce for capture. Specimens are identified by an entomologist and sent to the NJDOH laboratory for a combination of West Nile virus, Dengue Fever, and Chikungunya testing.
The Resting Box
Mosquito Control maintains a series of fifty plywood boxes, one cubic foot in volume and open only on one side, at a site near a cedar swamp to collect mosquitoes transmitting Eastern Equine Encephalitis. These mosquitoes are active overnight, feeding on blood from sleeping birds. As daylight approaches the mosquitoes seek a place to rest and avoid the drying effects of the sun. The resting boxes provide an artificial alternative to natural sites like hollow trees. Once a week (May through October), a staff member covers the box opening and sprays an anesthetic into the box. The collected mosquitoes are identified by an entomologist and sent to the NJDOH laboratory for a combination of West Nile virus and Eastern Equine Encephalitis tests.