BACILLUS THURINGIENSIS use as an insecticide for 25 years despite formidable competition from conventional insecticides is largely due to its safety and compatibility. mainly with natural control but also with chemical insecticides. For example. a chemical ovicide is frequently used in conjunction with Bt for early-season Heliothis control. This combination is particularly useful in districts where a mite problem. could be induced by the use of a broad spectrum. insecticide which would destroy the natural mite predators. In Thailand,. its use against cabbage moth larvae is essential because of resistance to all alternative insecticides.