Bacillus thuringiensis serotype H-14 deBarjac, at rates used for mosquito control, is very safe to organisms associated with mosquito breeding habitats. A total of 28 species or species groups was treated with the bacterium under simulated of field conditions; no adverse effects were noticed on the organisms, except Chironomid larvae. Chironomid larvae were slightly affected. However, the effect was so light that the population in the field continuously increased after the treatment.