Mosquito Control San Antonio combines point source reduction (removing breeding areas) and routine larviciding (killing mosquito larvae). Check outside items such as old tires, buckets, toys, and garbage cans for mosquito breeders.
Empty and scrub containers that hold water, such as vases, bird baths, and flower pot saucers, once a week. Treat these with Bti or other EPA-registered larvicides if they cannot be dumped or drained.
Stagnant water provides an ideal breeding habitat for mosquitoes. This is why the best way to fight them is by removing any sources of standing water from around your home. The most effective way to do this is to regularly inspect your yard for items that might hold water such as bird baths, plant saucers, trash containers, old tires, tarps and even discarded toys. These should be dumped, emptied or otherwise modified. It is also important to clean and scrub outdoor decorative accents such as fountains, ponds or other landscape features.
When you cannot discard or modify something, you should keep it in a container that is screened or covered to prevent mosquitoes from getting into the container and breeding inside. This can be done for items such as rainwater harvesting systems, but it is particularly important to make sure these are properly screened and that the overflow system conveys water to a drain or other area that will not harbor mosquitoes.
If you have a cistern, bucket, or other water collection container that can’t be discarded, use wire mesh to cover it and drain it on a regular basis. Also, regularly clean out gutters and downspouts so that they don’t clog and prevent water from pooling.
For backyard ponds and other landscape features, keep the water moving by using an aerator or pump to circulate the water. If possible, introduce mosquito-eating fish or use biological agents such as bacillus thuringiensis israelensis (BTI) in the pond water to control the mosquito larvae without harming plants or animals that depend on the pond for survival.
Similarly, for items such as tarps, buckets or other containers, cover them with mosquito-eating fish or BTI to control mosquitoes. If this is not possible, empty and scrub them regularly. It is also a good idea to use screens to cover any outdoor equipment such as air conditioning units or spigots, or to drain these periodically. This will help to control mosquitoes and other insects that can damage your landscaping and cause diseases such as canine heartworm.
Controlling Larval Mosquitoes
One of the primary tasks performed by organized mosquito control programs is to find and eliminate large larval habitats (source reduction). This can include impounding ponds, swamps and sluggishly moving streams or ditches. It can also mean removing aquatic vegetation such as cattails and water lettuce, or destroying mosquito eggs at the water’s surface.
Mosquito larvae must have access to atmospheric oxygen in order to grow and develop. They obtain it through a siphon tube that penetrates the water surface or, in the case of some species, pierces the roots of aquatic plants. Larvae develop in a series of stages called instars. Each instar lasts several days and a new instar is formed each time the larva takes in air through its siphon tube. If a larva cannot gain oxygen through its siphon tube, it will die. Larvicidal chemicals are used to kill mosquito larvae to prevent them from becoming adult mosquitoes that can bite people and spread disease. Larvicides are applied directly to bodies of standing water that contain mosquito eggs or larvae. EPA-registered larval insecticides are most commonly used as larvicides, but some organic materials also can be effective.
In addition to larviciding, the best prevention method is homeowner education. Mosquito control professionals speak to civic and community groups, attend press conferences, visit neighborhood yards and communicate with residents on a one-to-one basis to emphasize that steps can be taken to prevent mosquitoes and the diseases they transmit. These steps include dumping out or draining standing water that collects in containers such as tarps, flower pots and buckets after it rains. Window screening is another important tool that helps keep mosquitoes out of homes. And pet owners are urged to have their dogs and cats vaccinated against dog heartworm disease, which is transmitted by mosquitoes.
Potential breeding areas are inspected on a regular basis from March through September by trained personnel who can identify the presence of mosquito larvae to the species level. The locations of breeding sites are recorded on United States Coast and Geodetic topographic maps, and may be mapped at a more detailed city or county scale. Inspections are most critical following heavy rains and flooding tides, because mosquito larvae rapidly develop in the presence of saturated soil conditions.
Controlling Adult Mosquitoes
During their four-stage life cycle, mosquitoes (Culicidae) develop as eggs, larvae, pupae and adults. Only adults are capable of biting. To help reduce mosquitoes, empty or treat any standing water where they might breed. This includes rain barrels, bird baths, ponds, tire-wells, clogged drains, stormwater sumps and other natural or man-made containers.
Keeping grass mowed short, eliminating overgrown shrubs and hedges, and removing brush and debris are additional ways you can help control mosquitoes around your home. Many community mosquito programs provide spraying services using backpack sprayers, trucks and airplanes to control adult mosquitoes. These treatments use EPA-registered pesticides, known as adulticides, to kill mosquitoes and can be effective in reducing the number of mosquitoes that transmit diseases such as dengue, Zika, West Nile and eastern equine encephalitis.
Mosquito control activities rely on a combination of source reduction, larval control and insecticides that target adult mosquitoes to prevent disease transmission. The County monitors several mosquito-borne viruses that affect humans including Zika virus, dengue fever, chikungunya, and encephalitis caused by West Nile and St. Louis encephalitis viruses. Surveillance methods include monitoring for antibodies to these diseases in sentinel chicken flocks that are released throughout the county in areas where mosquitoes breed.
Aerial spraying for adult mosquito control is one of the fastest and most effective methods to control a serious outbreak of mosquito-borne disease or a very heavy nuisance mosquito infestation. EPA-registered adulticides (including the organophosphate insecticides malathion and naled, and the synthetic pyrethroid insecticides prallethrin, etofenprox, resmethrin and sumithrin) are applied either by aircraft or on the ground with truck-mounted sprayers.
During the day, mosquitoes rest in vegetation such as tall grass, shrubs and trees. When they are ready to feed, mosquitoes move through these shaded areas in search of a blood meal. Treating these vegetation with a residual product may help to further reduce mosquitoes at nighttime. Use only products labeled for residual mosquito treatment and read the directions carefully. Adding more product to the sprayer than directed or reapplying more often than recommended can actually make a residual spray less effective.
Using Insecticides
When surveillance activities indicate that mosquito populations are growing or that they’re spreading diseases, professionals use EPA-registered insecticides to kill adult mosquitoes. These insecticides, called adulticides, are applied using ultra-low volume (ULV) spray or fog. ULV equipment atomizes the active ingredient in the pesticide into small droplets, which are spread in a dense fog or spray and aimed where mosquitoes are flying to minimize exposure. ULV sprays contain very small amounts of the pesticide, and nozzles are carefully calibrated to match the size of the treatment area.
Mosquito control products to kill immature mosquitoes are also called larvicides or pupicides. They are used in aquatic habitats to reduce the number of mosquito larvae and pupae that survive and then develop into biting adults.
These products are very effective at killing immature mosquitoes, but do not harm other wildlife like birds or amphibians when used according to their label directions. However, the application method of these larvicides may cause runoff into natural waterbodies. Insecticides in runoff may be carried by stormwater, contaminated wastewater discharged from commercial or residential sites, or forestry land applications. Insecticides in runoff can enter wetlands and other waterbodies through spray drift during application, from washing application equipment, or by direct injection into the waterbody. Insecticides in the water can contaminate sediment or biota, and may be transported up the food chain to fish or amphibians that consume those organisms.
Insecticides may also enter the environment from other sources like application to cropland, or from spills or misuse of the product. Runoff from treated fields can carry the insecticides into lakes and rivers, or to wetlands where the chemicals may leach into groundwater supplies. The toxicity of the chemical will depend on its type, concentration, and how long it remains in the water or soil.
Homeowners can help prevent the need for aerial or ground applications of insecticides to kill adult mosquitoes by trimming weeds around house foundations and yards, and mowing lawns regularly. They can further reduce the number of mosquitoes harboring in vegetation by changing the water in birdbaths and wading pools at least once a week, and by stocking ornamental pools with top feeding predacious minnows such as Bti or S-methoprene (commercially available from most garden/hardware stores). These methods will not eliminate all adult mosquitoes. However, they can significantly decrease the amount of mosquitoes that are carried into the neighborhoods and homes to bite people.