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State of New Jersey - Department of Environmental Protection-Mosquito Control & West Nile Virus
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Mosquito Fact Sheet Questions and Answers
What types of mosquitoes are known to transmit the West Nile Virus?
How does the mosquito transmit the West Nile Virus?
How are the mosquitoes tested?
Describe the various methods of surveillance used to trap mosquitoes?
What types of spraying for mosquitoes take place during the year and where?
How do mosquito control agencies know how, when, and where to treat?
What type of insecticides/pesticides are used?
Are the insecticides/pesticides used for mosquitoes safe?
What power does the State have over businesses or individuals with discarded tires in the yard? Does the State spray?
Does the State control mosquitoes, or do the counties?
What is the Biological Control Program? How does this work at the county level?
When can we expect the mosquitoes to emerge? How do they lay their eggs?
What time of year do mosquitoes stop taking blood meals?
How far do mosquitoes typically fly?
Now that we know West Nile Virus can survive New Jersey winters and reappear in the spring, is the disease here to stay?
What is New Jersey doing to control the mosquito population should the virus return?
Are the State's health advisories to avoid areas with high concentrations of mosquitoes an indication to cancel outdoor activities in the evening?
Will my entire county, or the state, be sprayed either by trucks or aircraft?
How do these pesticide regulations protect me (and the environment)?

FAQ Answers
  1. What types of mosquitoes are known to transmit the West Nile Virus?
  2. ANSWER: The northern house mosquito, Culex pipiens, found in urban and suburban areas. The female mosquito lays its eggs in any receptacle containing stagnant water such as tires, birdbaths, children's toys, buckets, flower pots, clogged rain gutters, and plastic wading pools. A single container can produce tens of thousands of mosquitoes over a season. Female mosquitoes prefer to lay eggs on water that may be described as aged, stagnant and putrid. A well maintained swimming pool filled with clear, clean water is unlikely to breed mosquitoes. West Nile Virus has also been found in several species of floodwater mosquitoes, common in floodwaters like the meadowlands, woodland pools, flood plains and marshes. It has also been isolated in mosquito species which breed in discarded tires.

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  3. How does the mosquito transmit the West Nile Virus?
  4. ANSWER: Scientific evidence suggests that a mosquito bites an infected bird and may become infected with the West Nile Virus. If the infected mosquito then takes a blood meal from a human, the West Nile Virus may be transmitted to the human. For more information about the virus visit http://www.cdc.gov/ncidod/dvbid/arbor/arboinfo.htm.

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  5. How are the mosquitoes tested?
  6. ANSWER: Adult mosquitoes are collected in specially-designed traps. These specimens are transported into the laboratory where they are processed into collection "pools". A "pool" is simply a collection of adult mosquitoes that happen to all be the same species collected from the same location. A pool may contain hundreds of adult mosquitoes or only a few. The pool is then tested for the presence of the virus. Within the pool, even if only a single mosquito is infected, a positive result is reported for the whole pool.

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  7. Describe the various methods of surveillance used to trap mosquitoes?
  8. ANSWER: The standard trapping method used in this State is a device called the NJ Light Trap. In appearance it resembles a cone shaped cylinder about a foot and a half tall. It contains a light, a fan and a collecting receptacle. Collections of mosquitoes are made daily. Counties use a network of these throughout the State. This device, and others, are used to collect ADULT mosquitoes. Water samples are taken routinely as well to detect the presence of LARVAE in suspected breeding sites. Trained mosquito surveillance specialists use over a dozen different methods to survey for mosquitoes. Since the outbreak of West Nile Virus, several other collection devices and techniques have been applied to mosquito surveillance.

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  9. What types of spraying for mosquitoes take place during the year and where?
  10. ANSWER: There are several different kinds of spraying conducted during the year. All counties usually conduct larviciding on water surfaces from the ground as a preventative step before adult mosquitoes are hatched. Sometimes it is necessary to conduct larviciding by air if extensive water surfaces are involved. Controlling the adult mosquito is usually done by spraying an ultra low volume of insecticide. THIS IS DONE ONLY AS A LAST RESORT AND USED FOR ADULT MOSQUITO CONTROL IN RESIDENTIAL AREAS. Pesticide application technicians are certified by the State. New Jersey uses integrated pest management strategies, including larvae and habitat surveillance and water management, before resorting to aerial spraying. All aerial applications are directed toward confirmed mosquito populations which have the potential to create a major public nuisance or pose a threat to human or animal health.

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  11. How do mosquito control agencies know how, when, and where to treat?
  12. ANSWER: County mosquito control agencies utilize a variety of surveillance techniques which give them specific information about the location and size of mosquito populations. This information will assist them in timing and locating their insecticide applications.

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  13. What type of insecticides/pesticides are used?
  14. ANSWER: Mosquito control agencies in NJ use insecticide/pesticide formulations, which have been registered with the United States Environmental Protection Agency (USEPA) and the NJDEP, and have been recommended by Rutgers University. The selection of a specific pesticide is dependent upon the habitat of the breeding site, the stage of development of the mosquito during its life-cycle and the environmental conditions encountered by the certified applicator at the time. Recommended larvicides include biological based formulations such as B.t.i., organophosphates such as temephos and bio-rational juvenile hormones such as methoprene. Recommended adulticides include organophosphates such as malathion and synthetic pyrethroids such as resmethrin. Each formulation is applied at the minimum rate recommended on the label and in such a manner as to control only the mosquito at its most susceptible stage. Fact sheets on the pesticides used in New Jersey may be found at http://www.epa.gov/pesticides.

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  15. Are the insecticides/pesticides used for mosquitoes safe?
  16. ANSWER: Insecticides/pesticides are recommended by the NJ Agricultural Experiment Station at Rutgers University based on many decades of experience and research and only if registered with the United States Environmental Protection Agency (USEPA). Certification and training of applicators by the NJDEP stresses the correct and proper application of these materials. For further information about insecticides contact NJDEP's Pesticides Control Element at 609-984-6507. The insecticides recommended by Rutgers University's Agricultural Experiment Station may be found at http://www-rci.rutgers.edu/~insects/bmpmcnj.pdf.

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  17. What power does the State have over businesses or individuals with discarded tires on their properties?
  18. ANSWER: The inspection of tires for evidence of mosquito breeding and eventual control of mosquitoes is very difficult and labor intensive. Many counties, however, do attempt to address this issue in several ways including the application of larval control formulations. The elimination of these breeding sites would be the ideal solution to the problem. For more information about tire piles contact the NJDEP Bureau of Recycling and Planning at 609-984-3438.

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  19. Does the State control mosquitoes, or do the counties?
  20. ANSWER: Each of the 21 counties in New Jersey has a mosquito control program. The state has several programs that supplement the county mosquito control programs. The NJ State Airspray Program is funded by the New Jersey Mosquito Control Commission and administered by the NJDEP Office of Mosquito Control Coordination. It provides a variety of contracted aircraft for the application of larvicides and adulticides spread over inaccessible areas as requested by the counties and based on need. In addition, the State has various types of equipment ranging from low-ground pressure hydraulic excavators for marsh management projects, to lab equipment for mosquito-related research and control projects. Some 130 pieces of equipment are available free-of-charge to mosquito control agencies statewide. State-funded programs are intended to supplement and aid county control programs, not replace them.

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  21. What is the biological control program? How does this work at the county level?
  22. ANSWER: It is the use of natural predators, parasites, and pathogens to eliminate or control mosquitoes. The NJ State Mosquito Control Commission funds a Biological Control Program which uses five species of mosquito-eating fish which are raised at the DEP’s Division of Fish, and Wildlife’s Charles O. Hayford Hatchery in Hackettstown. These fish are distributed at no charge to county mosquito control agencies. Where practical, these fish control mosquito populations and reduce the need for pesticides. For more information on bio-control, read "How to Use the State Bio-Control (Mosquitofish) Program for Mosquito Control in New Jersey". (In Adobe Acrobat PDF format. The PDF files require a free PDF viewer available from Adobe.)

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  23. When can we expect the mosquitoes to emerge? How do they lay their eggs?
  24. ANSWER: The emergence of mosquitoes from the aquatic habitat depends on water and air temperatures but, IN GENERAL, adults are on the wing by April or May. The larvae hatch from eggs in the water and remain there during development, approximately 5-7 days. The larvae then go through the pupal, or resting stage, for approximately 1 day. Afterwards, adult mosquitoes emerge from this stage in the water and take flight. Adult male and female mosquitoes then mate. Once the female has mated she looks for a blood meal which she uses to develop a batch of eggs and the entire life-cycle is started over again when she lays a batch of eggs either directly on the water surface, or in areas prone to flooding. Only the female bites; the male does not bite. The female needs to mate only once. Female mosquitoes live for about six weeks. The male’s life is shorter. In general, upon the first hard frost most adult mosquitoes die. But, Culex pipiens can over winter as adults indoors in places such as attics and basements.

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  25. What time of year do mosquitoes stop taking blood meals?
  26. ANSWER: Host-seeking (the taking of a bloodmeal) is very temperature dependent. Once the air temperature falls below 60 degrees and the light-dark cycle shifts in the Fall, this behavior ceases.

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  27. How far do mosquitoes typically fly?
  28. ANSWER: Flight ranges of mosquitoes vary from species to species. There are over sixty species in NJ. Some seldom fly more than a few feet from their resting habitat; some fly over fifty miles in search of a bloodmeal.

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  29. Now that we know West Nile Virus can survive New Jersey winters and reappear in the spring, is the disease here to stay?
  30. ANSWER: Since West Nile Virus is new to this continent as of 1999, no one can predict how long it will be present in the animal (and human) population. In others parts of the world it may exhibit a cyclical presence over time or a semi-permanent one. New Jersey will have to continue a constant surveillance effort, with vigilance, in order to determine the year-to-year behavior of this disease.

    For more information about the epidemiology of West Nile Virus, contact the N.J. Department of Health at 609-588-3121. For information about mosquito biology contact the Center for Vector Biology, Mosquito Research Program at Rutgers University at 732-932-9341 or visit the Centers for Disease Control and Prevention at http://www.cdc.gov.

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  31. What is New Jersey doing to control the mosquito population now that we know the virus has returned?
  32. ANSWER: In New Jersey, the legislation that established mosquito control, did so at the level of county government. All 21 counties have a mosquito control program of some kind. This network of county agencies interact with state government via the Departments of Health, Environmental Protection and the Agricultural Experiment Station at Rutgers University. New Jersey has a comprehensive plan for dealing with a possible return of the West Nile Virus. It includes enhanced mosquito control efforts; increased human, animal and mosquito surveillance; a streamlined system for testing collected samples, and a public education program. Please refer to the New Jersey Department of Health's web site for further details.

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  33. Are the State's health advisories to avoid areas with high concentrations of mosquitoes an indication to cancel outdoor activities in the evening?
  34. ANSWER: Please check the New Jersey Department of Health’s web site at http://www.state.nj.us/health for advisories and information.

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  35. Will my entire county, or the state, be sprayed either by trucks or aircraft?
  36. ANSWER: New Jersey's approach to mosquito control (and therefore West Nile Virus control) is one that applies the accepted practice of Integrated Pest Management (IPM). This strategy depends on a multidisciplinary approach that includes many control strategies including, but not limited to, the application of pesticides. The basis for any control is a comprehensive survey of the mosquito population county-to-county. The better the surveillance program, the more specific and local control measures can be, rather than a "blanket" approach countywide. When pesticide applications become necessary, whether by truck, helicopter or airplane, they are usually made for the control of larvae in specifically identified bodies of water only. Most pesticide applications are of this type. If the adult mosquito populations threaten the human, domestic animal or wildlife populations, or if the state or federal government recommends adult mosquito control applications take place, then they are performed according to the state and federal pesticide regulations.

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  37. How do these pesticide regulations protect me (and the environment)?
  38. ANSWER: By law, any pesticide application made for mosquito control in New Jersey must be performed by a New Jersey certified pesticide applicator or operator. Applications must be of products registered by both the NJDEP and the USEPA. This state also requires that the only pesticides used are those recommended annually by the New Jersey Agricultural Experiment Station at Rutgers University which has carried on research of available products since 1912.

    Further, if pesticide applications are scheduled in neighborhoods for the control of ADULT mosquitoes or if aerially applied LIQUID applications are scheduled, county mosquito control agencies are required to notify residents who request notification prior to the scheduled pesticide application. Further information about New Jersey pesticide regulations may be found at http://www.nj.gov/dep/enforcement/pcp/. A listing of all 21 county mosquito control agencies can their contact phone numbers may be found at http://www.nj.gov/dep/enforcement/pcp/bpo-mfagencies.htm.

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Last Updated: July 24, 2012