General Information

Since the beginning of civilization, no member of the Animal Kingdom has had such a wide and devastating influence on man and his way of life as the mosquito.  Mosquito-borne diseases are among the world's leading causes of illness and death today.  The World Health Organization estimates that world-wide more than 300 million clinical cases and almost 4 million deaths each year can be attributed to mosquito-borne illnesses.

The deadliest diseases occur mostly in tropical regions of the world such as Africa, Asia and South America.  The most devastating diseases are malaria, dengue fever, and yellow fever.  Although there are only occasional cases of those diseases in the United States, mosquitoes here can still cause illness and death in people and animals.  Some of the mosquito-borne diseases we are concerned with in California are St. Louis Encephalitis (SLE), Western Equine Encephalomyelitis (WEE), dog heartworm and West Nile Virus(WNV).

There are about 2,500 different species of mosquitoes worldwide, 53 species in California and 10 species in the Antelope Valley.  The "house mosquito" (Culex quinquefasciatus) and the "encephalitis mosquito" (Culex tarsalis) are the most common species in the Antelope Valley.  They are both capable of transmitting West Nile Virus to animals and humans.

All mosquitoes need water to complete their life cycle, muddy or grassy areas will not produce mosquitoes.  A female mosquito will lay her eggs on or near water, the larvae and pupae live in the water and then the adult emerges out of the water about 5-7 days later. 

Only female mosquitoes bite people and animals, because they need the blood to produce eggs.  During this blood meal they may transmit viruses or other pathogens that can lead to potentially severe illness.  Therefore the best defense for mosquito-borne diseases is avoiding mosquito bites by using insect repellents (see below) or wearing long-sleeved shirts and pants when mosquitoes are active.

Both male and female mosquitoes will drink nectar and fruit juices for nutrition.



Mosquito Life Cycle

Mosquito larvae occur in almost any stagnant water, like catch basins, street gutters, unkempt pools, artificial containers, cemetery vases and even in foul water such as septic tanks and dairy ponds.

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Tips to keep yourself and your loved ones safe from mosquito-borne diseases*:

1. Check your property for stagnant water and make sure you are not creating a mosquito habitat. Fix sprinklers, dump or drain standing water once a week, keep pools maintained or drain them.
2. Report unmaintained or vacant pools to us so we can kill the mosquitoes.
3. Wear insect repellent if you are outdoors when mosquitoes are active. The CDC recommends  using products containing DEET, Picaridin, Oil of Lemon Eucalyptus or IR3535 (more information).
4. Make sure window and door screens are in good shape and repair if needed to maintain a tight fit. 
5. Report dead birds to the State hotline at westnile.ca.gov/report_wnv.php

*Diseases like malaria, encephalitis, yellow fever, dengue, heartworm, elephantiasis

Disease Surveillance

California has one of the most extensive mosquito surveillance systems in the entire Nation.  This is due to the cooperation of the California Department of Public Health (CDPH), California Food and Agriculture, the University of California, and the Mosquito and Vector Control Association of California(MVCAC). The MVCAC is made up of over 60 special districts and local public health agencies throughout California to provide quality public information, comprehensive mosquito and vector-borne disease surveillance, training to high professional standards, and effective legislative advocacy on behalf of California mosquito and vector control districts.

The Antelope Valley Mosquito & Vector Control District conducts surveillance to identify increased mosquito activity as well as an early detection system for mosquito-borne diseases.  The diseases that we routinely check for are St. Louis Encephalitis (SLE), Western Equine Encephalomyelitis (WEE), and West Nile Virus (WNV).  We utilize three different types of mosquito traps and eight chicken coops with sentinel chickens throughout the district. 

New Jersey Light Traps: These are stationary traps that are strategically placed in 13 locations in the district from early April through October.  They capture mosquitoes and other insects by attracting them with light and then sucking them into a jar with a fan.  They are collected once a week and the mosquitoes are identified and counted to track population density in those areas.  Since these mosquitoes are dead when picked up they cannot be used for virus detection.

 EVS / CO₂ baited Traps: The encephalitis vector surveillance (EVS) traps use dry ice (CO₂) as a bait to attract host-seeking  

female mosquitoes.  EVS traps are used mainly to determine whether SLE, WEE or WNV occurs within a localized area.  During mosquito season, traps are set overnight once a week at variable locations throughout the District to capture mosquitoes.  These live mosquitoes are identified, counted and then sent to the  California Department of Public Health to be tested for SLE, WEE, and WNV. 

    
Reiter Gravid Trap: The Reiter trap uses hay infused water to attract gravid (pregnant) blood-fed mosquitoes.  These traps are set out at the same time and in close proximity to the EVS trap sites.  Reiter traps are also important in collecting mosquitoes for virus testing, because the blood-fed mosquitoes are more likely to contain virus.  The mosquitoes are also sent to CDPH for testing.

Sentinel Chickens:  The sentinel chicken flocks serve as an early warning system for the detection of SLE, WEE, and WNV transmitted by mosquitoes within the district boundaries.  Blood samples are taken bi-weekly from the sentinel chickens and analyzed by the CDPH’s Viral and Rickettsial Disease Lab to determine the presence of virus antibodies, indicating whether mosquitoes in the area have transmitted a virus that could potentially infect people and animals. This early detection allows us the increase our control efforts and public outreach to prevent the human infections.  The AVMVCD utilizes 8 flocks throughout the district.

 Dead Bird Surveillance:  Several bird species die after being infected with WNV and can therefore serve as another early warning system.  The California Department of Public Health coordinates a statewide surveillance of dead birds.  They can be reported online or by calling 1-877-WNV-BIRD (968-2473).  District personnel will pick up the birds and send them to the State lab if they qualify for testing – they have to be intact and dead less than 24 hours. 

If birds are not picked up by the end of the day you can safely dispose of them in the garbage.

Mosquito Control

All mosquitoes need water to complete their life cycle.  These bodies of water are usually very well defined and rather small areas, such as retention basins, ditches and swimming pools.  Even bucket of water or a discarded water bottle can serve as mosquito breeding place and can produce hundreds of mosquitoes.  Once they hatch out as adults, they fly up to a mile from their original habitat and occupy a much larger space.  Therefore we target the mosquito larvae and pupae that live in the water in our control efforts.

This is the most efficient way to reduce the number of mosquitoes, and sometimes it’s as easy as dumping out a bucket of water or clearing debris from the street gutter to make the water flow freely.   When necessary, we use pesticides that are environmentally friendly and very target specific, so they will only affect mosquitoes.  This is part of our Integrated Pest Management (IPM) program.

Our technicians are assigned to specific areas within the district.  Standing water in street gutters, ditches and retention basins are checked weekly and treated when needed.  If the water is in plain sight we already know about it and it is part of their regular route, so you don’t need to report it.  If you are aware of water sources that are not easily seen such as un-maintained backyard pools or ponds, please notify us so we can check it out.

For more information on pesticides used in mosquito control check out the National Pesticide Information Center at: http://npic.orst.edu/pest/mosquito/mosqcides.html.

A Joint Statement on Mosquito Control in the United States from the U.S. Environmental Protection Agency (EPA) and the U.S. Centers for Disease Control and Prevention (CDC) is available at:  http://www.epa.gov/pesticides/health/mosquitoes/mosquitojoint.htm.

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Mosquito Fish (Gambusia affinis)



             

Mosquito fish (Gambusia affinis) are small, guppy-like fish, which are expansively used in modern mosquito control programs. They feed primarily on aquatic insects and prefer mosquito larvae. Gambusia are able to mature, reproduce and survive quite well in a variety of water conditions, which makes them perfect to stock in permanent mosquito breeding sources. They are able to tolerate moderately high levels of salt, algae, pollutants, and a temperature range from nearly freezing to above 100 degrees Farenheit. Mosquito-fish are compatible with most ornamental pond fish, including Goldfish, Koi and Carp. This makes them an excellent addition to any fish pond with shallow areas and vegetation, that the bigger fish cannot penetrate to eat the mosquito larvae.


Female mosquito-fish produce eggs that hatch within their bodies, releasing 30-100 well developed young, called "fry" into the water. Young mosquito-fish are about one half inch in length when born and immediately begin eating mosquito larvae. They grow rapidly in the sumer and reach a maximum size of 1-1.5 inches in males and 2.5 - 3 inches in females. Gambusia breed throughout the summer and a new brood is produced at 4-6 week intervals. The young fish reach maturity in about 4-5 months.

The Antelope Valley Mosquito and Vector Control District stocks thousands of these fish each year in artificial ponds, ditches, retention basins, and drainage channels to eliminate the need for frequent treatments with mosquito larvicides. Residents of the district can get mosquito-fish for free to stock their ornamental ponds, animal watering troughs, and unused swimming pools.
Please call ahead to make sure there are enough fish available.