Larvaciding is the practice of killing mosquito larvae with stomach or contact poisons.   Larvacidal control is of primary importance where control of pest or disease-carrying mosquitos is necessary, particulary in situations with extensive flooding following natural disasters or prolonged rainy seasons.

The synthetic organic insecticides can be applied as dusts, pellets and granular formulations, wettable powders, solutions, or emulsions.  The city of Jamestown uses larvacide in pellet and granular formations.  These have a larger particle size than the other forms.  They slip through leaves or dense vegetation and reach the water surface to kill mosquito larvae. 

Here in Jamestown we use the larvacide Altosid.  It is an insect growth regulator, not an outright poison.  Insect growth regulators have been studied intensively in recent years.  Some of them have been called insect development inhibitors, or juvenile hormone-like materials.  Some inhibit molting of mosquito larvae; others cause mortality in the pupal stage.  At the present time, only two of these compounds have given good results in the field.  The first, Altosid, has been granted an EPA label for mosquito control, while the second, TH-6040, is currently being used on an experimental label. 

It is recommended that the larvacide be a different chemical from that used for adult control (currently Jamestown uses Anvil for adult mosuito control).   The degree of control with larvacides differs with the various species of mosquitos, degree of pH and pollution of water, and type and amount of vegetation present.  

    *This material is directly quoted from Mosquito Control Guide, provided by VAN DIEST SUPPLY COMPANY, 6th Edition; and MOSQUITOES OF PUBLIC HEALTH IMPORTANCE AND THEIR CONTROL, provided by the Department of Health, Education, and Welfare by the Public Health Service's Center for Disease Control