Q and A: I have heard that there is a type of mosquito that is an indicator for poor water quality. What are these mosquitoes called and do they exist in this area?

from C.R., Bonita Springs

Blind mosquitoes, also known as aquatic midges, are mosquito-like insects often associated with poor water quality. Blind mosquito is a common name that may refer to various species of midges. One thing to keep in mind is that even though these insects MAY be an indicator of polluted water, blind mosquitoes do not bite, suck blood, or carry disease. They effect people as a nuisance when they emerge in large numbers between April and November.

Blind mosquitoes are one of the most common and abundant organisms in natural and man-made water systems. Therefore, they may exist in the area. The first three life stages (egg, larva, and pupa) have some contact with water. The eggs are laid on the surface of the water and attach to twigs or the edge of the water body. If the eggs do not attach to something they sink to the bottom and hatch there instead. In Florida, the larvae can be found in small and large natural lakes, wastewater channels, sewage oxidation and settling ponds, and residential/recreational lakes. The larval stage may last two to seven weeks depending on the water temperature. The pupal stage lasts about three days before the adult emerges. Adults do not feed so they only live for three to five days.

When large numbers emerge, humans may stay indoors to avoid having the mosquitoes fly into mouths, eyes, or ears. These mosquitoes may stain paint, stucco, and other finishes. They may cover windshields on automobiles decreasing visibility. After mating flights, there may be an abundance of dead carcasses soiling sidewalks and porches. If the blind mosquitoes fly into a residence, they can stain laundry, walls, ceilings, draperies, and other furnishings. Spider webs and spiders are common when these mosquitoes persist. Homes and businesses may have to be washed since dead midges smell similar to rotting fish. The smell may continue in damp weather even if the midges have been washed away. On the other hand, blind mosquitoes are an important part of the food chain since fish utilize the larvae for food. These insects are such a good source of food that breeding locations are some of the best fishing sites.

Extensive research has been compiled on the control of blind mosquitoes. Blind mosquito larvae are difficult to kill since total treatment of the water body is required. With increased resistance to pesticides and the concern over environmental quality, larval control is not feasible. The mosquito control district should carry out area control of blind mosquitoes. Individuals may use fogs or mists to kill mosquitoes nesting along the shoreline or in the grass, but should follow the product instructions closely. All control measures are temporary. Effluents from food-processing plants, septic tanks, sewage treatment facilities, and leaching fertilizers from lawns and agricultural practices apply nutrients that contribute to food production for these mosquitoes. As pollution increases, food increases, and so do insect populations. If a waterway is severely polluted the blind mosquitoes will not survive. The long-term control solutions may be to reduce effluent that provides food, increase effluent until the mosquitoes cannot survive, or introduce biological controls to eliminate populations. Humans are part of the reason these mosquitoes have become such pests. Our desire to live near water has increased the number of man-made lakes and water pollution, therefore increasing the habitat for blind mosquitoes.


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