Screening programmer to isolate strains of the genusrnBacillus for their potential use in the control ofrnmosquitoes was done. Over 90 spore-forming bacillusrnstrains were examined. Six isolates AA-2, AA-6, AA-10,rnAA-l1, AA-71, and AA-82) have shom killing ability ofrnwhich four (AA-2, AA-11, AA-71, and AA-82) were found tornbe effective. Biochemical and morphologicalrncharacterizations have revealed similarity rnbetween these isolates and the Well Known mosquito pathogensrn(B. thuringiensis ancl B. sphaericus). rnThe effect of temperature and aeralion supply onrnbiomass production was studied. Isolateswere found torndliffen:nlly responcl to temperJIUle. Isol"Ias fnunurnto qroâ€¢: h'l'll at 30')C. A,;-ll 11ds been found to huve a widerange of rntemperature (23- 40)AA-71 has Sl10WIl io'ersernrelation ,ith temperature, h'hereas isolate "A-82rndemonstrated critical decrease in growth with increase inrntemperature and 30~ was found to be optimal. Dry biomassrnwas founcl to increase with the increase in aeration levels.rnThe efficacy of the isolates was tested on differentrnlarval stages of mosquito. LC IO that ranged from 43-170rnllg/ml ,as obtained. ~o siqnificant difference has beenrnobserved in sensitivity of different larval stages ofrnmosquito to different bacteria at a significance level ofrn1% except isolate AA-11. Efficacy of the isolates underrnnatural conditions was also tested. Some strains (eg.rnAA-82) have shown good results.Further confirmatoryrn characterization is needed as wellrnas investigation for optimal conditions to increase toxin yield.