Mosquito Larvicides

Bacillus thuringiensis subspecies israelensis (Bti) is a naturally occurring  bacterium found in soils. It contains spores that kill mosquito larvae (and blackfly and fungus gnat larvae), but is harmless to other living things including animals, plants, and people. Bti has been found to be very effective in reducing mosquito larval populations. 

Bti is used for mosquito control by the Vector Control Program, and is also available for residential mosquito control. It can be put into standing water, like rain barrels, ponds and fountains, to prevent development of larvae. It is available to purchase in hardware and garden stores in many different forms including: briquettes, granules, liquids, tablets, and pellets.

Adding Bti to standing water can prevent mosquito breeding and the spread of mosquito-borne diseases. 

rain barrel


  • Bti larvicides are ideal for treating rain barrels, ponds, and fountains to prevent mosquito breeding.
  • Treat the water collected between the leaves of bromeliad plants with a liquid Bti larvicide to eliminate larvae.
  • Use granule larvicides in small containers like the saucers under potted plants. 
  • For best results, use products at the frequency indicated by the label.
  • Follow all safety instructions on the product label.


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