Mosquitoes are found in a variety of habitats...
Larval surveillance is one of the most important aspects of a mosquito control program. With continuous surveillance of larval habitats, mosquito population surges can be predicted and often abated through the well-timed application of larvicides. Additionally, knowledge of mosquito-breeding sites can increase adulticide efficacy because these areas can be selectively targeted before adult mosquitoes disperse to nearby areas.
Larval habitats (permanent water, temporary pools, drainage ditches, septic ditches, catch basins, artificial containers and tree holes) should be inspected regularly and mapped into a GIS database using GPS technology.
Permanent Water sites consist of habitat that remains inundated for an extended period of time. Examples of these sites would be lakes, rivers, retention ponds, swamps, etc. Permanent water sites will be inspected on a routine basis throughout the mosquito-breeding season. These areas are capable of producing large numbers of various species of mosquitoes such as Anopheles crucians, An. quadrimaculatus, Coquilletidia perturbans, and Culex restuans.
Temporary Floodwater is standing water that may exist for short periods of time after high water or rainfall. Examples of this type of habitat would include bottom lands, woodland pools, swales (low areas), drainage ditches, tire ruts, and depressions. Large numbers of mosquitoes can be produced in a short period of time from these sites. These areas must be inspected for the presence of larvae as soon as possible after every substantial rainfall. Mosquitoes expected to be found at these sites include Aedes vexans, Ochlerotatus canadensis, Psorophora columbiae, Ps. howardii, Ps. ciliata, and Ps. ferox.
Artificial Containers/Tree Holes are considered one of the most troublesome problems faced by a mosquito control operation. Artificial containers can be found everywhere and produce mosquitoes in nearly every back yard. Anything that holds water can produce artificial container species. Old tries, cans, bottles, buckets, cups, pet water bowls, birdbaths, gutters, and swimming pools are some of the more common artificial containers. From this type of habitat comes one of the top pest species - Ae. albopictus (commonly referred to as the Asian tiger mosquito). Additional species that occur in artificial containers include Culex pipiens, Cx. restuans, Cx. erraticus, Ochlerotatus triseriatus, Ae. aeqypti, Orthopodomyia signifera, and Toxorhynchites rutilus septentrionalis. As private and public properties are inspected, container habitats should be checked and removed/emptied as needed.
Septic Water Habitats occur when water holding areas become polluted with high levels of organic matter. Examples of this type habitat would include oxidation ponds, ditches with sewage discharge or run off from decaying plant or animal life. Septic water can often produce the largest number of mosquitoes per unit of area. Culex quinquefasciatus and Cx. pipiens are often the most common species found in this habitat, and are also the primary vector for West Nile virus in the United States. Routine management of this habitat type and the control of encephalitis vectors are vital to public health.
Catch Basins occur throughout urban areas and are capable of breeding numerous mosquito species. Of primary concern in these habitats is Cx. quinquefasciatus and Cx. pipiens, the primary vectors of West Nile virus. Although all catch basins may hold water at some point in time, not all catch basins are sites of prolific mosquito breeding. Improper drainage, poor design, and amount of rainfall can all contribute to the number of mosquitoes produced in catch basins. Catch basins should be assessed for mosquito breeding and where appropriate treated.
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Larval Surveillance