Bacillus thuringiensis (Bt) microbial insecticides, used in combination with ovicides and/or synthetic pyrethroids (SP's) show promise as an alternative to using "hard," broad spectrum Synthetic organic Insecticides (SOI's) which can cause reduction in beneficial insect populations. Newly developed third generation Bt's have shown to be more potent, palatable and selective than currently available commercial Bt's. Extensive (75,000 acres), practical field use of low dosages of Bt's in combination with reduced rates of SOI's beginning very early season, (pre-square initiation), are proving to be more cost and control effective than SOI's used alone.