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 either a briquet or granular form (Look for a product like Mosquito Dunks or Mosquito Bits).

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

rain barrel


  • Bti larvicides are perfect for treating rain barrels, ponds, and fountains to prevent mosquito breeding
  • Sprinkle granular larvicide into the water collected between the leaves of  bromeliad plants to eliminate larvae
  • For best results, use products such as Mosquito Dunks once a month and granular products such as Mosquito Bits every 7-14 days.
  • Follow all instructions on the product label

More information about the safety of Bti:

Environmental Protection Agency (EPA)


Mosquito Dunks
Mosquito Bits