The microorganisms which present on the clay soils, were studied. The result recorded that bacteria isolated from clay soils were identified Bacillus thuringiensis, E. coli, Pseudomonas, Klebsiella and Shigella. The B. thuringiensis is the highest bacteria causing mortality reached 100% to house fly and mosquitoes, while other bacteria causing 30%, zero%, zero% and zero% mortality for E. coli, Klebsiella, Pseudomonas and Shigellarespectively. Most strain of Bacillus thuringiensis isolates produce a typical crystal often heterogenous in size and shape. Extraction of total DNA from B. thuringiensis isolate for PCR analysis was done. All B. thuringiensis isolate were characterized by PCR. Parasporal bodies of B. thuringiensis isolates had biological activity when assayed againsthouse fly and mosquitoes. Field application of B. thuringiensis as toxic spray on poultry houses by using 2 x 103 c.f.u/m showed that mortality of mosquitoes reached 100% after 4 days. It can be concluded that Bacillus thuringiensis (BT) are bacteriocidal causing mortality reached to 100% after 4 days post-treatment with concentration of 2 x 103 cfu/ml. respectively. Most strain of Bacillus thuringiensis isolates produce a typical crystal