Every summer, thousands of Virginians complain to their local and state government officials about the horrible mosquito problems they have in their neighborhoods. Often, a nearby pond, puddle, flooded ditch, marsh or swamp are the focus of the mosquito complaint. However, in most cases the problem mosquitoes turn out to be Asian tiger mosquitoes and the source of these mosquitoes is found to be containers of water on or near the citizen’s property.
Asian tiger mosquitoes are what is known as a container breeder. That is because its aquatic breeding habitats are strictly comprised of artificial or natural containers that hold water. Asian tiger mosquitoes will not lay their eggs in [breed in] puddles, flooded ditches, natural ponds, marshes, swamps, or any body of water with a natural soil substrate. Mosquito breeding containers of water can include: buckets, plastic cups, trash can lids or trash cans, ceramic or plastic plant trays, ornamental [plastic lined] ponds, old tires, boats, bird baths, wading pools, rain barrels, plastic toys, glass bottles or jars, clogged roof gutters, corrugated black plastic downspout extension pipes, tree holes [i.e., knot holes or forks in tree trunks that hold water], rock pools [i.e., holes in large stones that hold water] etc. In shady neighborhoods, trees reduce the amount water evaporation from their aquatic "container" habitats by providing shade and reducing air flow. A container holding a gallon of water and sitting in the shade will still hold water months later even if there has been no rain. An Asian tiger mosquito larva can complete its development into an adult biting mosquito in as little as a tablespoon of water.
Asian tiger mosquitoes are only active during daylight hours [up through dusk], but do not like to spend too much time in open sunlight. Therefore, their populations are more of a problem in neighborhoods that have a lot of shade. Tiger mosquitoes spend a lot of time sitting in the foliage of a bush or shrub, waiting for a person, cat, or dog to walk by before they fly out to bite. They are persistent in their attempts to feed, but are not bold (i.e., they will not just fly up and bite a person on the nose or face like some mosquito species do). Instead, they are cautious and sneaky, preferring to bite ankles, and the back sides of arms and legs.
Asian tiger mosquitoes can be a potential health threat as they are able to transmit a number of mosquito-borne diseases. In Virginia, these diseases include West Nile virus, La Crosse encephalitis, and Eastern equine encephalitis. They could also be important vectors of tropical diseases like dengue and chikungunia if and when these diseases get imported into Virginia.
Unfortunately, control of Asian tiger mosquitoes by county mosquito control programs is difficult because the truck mounted foggers [aerosol sprayers] traditionally used for mosquito control only kill the mosquito species that are in active flight. As Asian tiger mosquitoes fly very little, and spend most of their time sitting in foliage, waiting for a meal to walk by, they are poorly controlled by such sprays. To have an impact, aerosol sprays would have to be directed with some velocity into all shrubberies and foliage from close range in each yard [i.e., by people with back-pack foggers].
The best tiger mosquito control efforts involve teams of people going house-to-house to find and dump, or treat all the container breeding habitats at each residence and to educate the residents. This activity can be combined with back-pack fogging or the application of barrier sprays (i.e., residual insecticides sprayed on bushes to prevent mosquitoes from landing or resting there). However, this type of control activity is generally too intensive and costly for most municipalities to afford, and if home owners are not educated or involved in the process, it would have to be repeated each year or possibly several times a year for many years to come. Neighborhoods can also form their own organizations to eliminate tiger mosquito breeding habitats, and this cooperation between neighbors can be quite effective. Educated residents will breed fewer Asian tiger mosquitoes on their properties than those who have no understanding of the biology of this species.
If you are having problems with mosquitoes in your neighborhood, focus on container habitats first. They are most usually the source of the problem mosquitoes. Reducing or eliminating the production of mosquitoes around your home will help you and your neighbors have a safe and enjoyable outdoor life this summer.