A seven-year field study of the nontarget impacts from applications of Bacillus thuringiensis kurstaki (Btk) to control gypsy moth is summarized. Btk treatments caused significant declines of lepidopterans, but Btk’s impact was dependent on the caterpillar stage being exposed through feeding on treated foliage. Some indirect impacts on natural enemies of caterpillars removed by Btk treatments were also significant. Recovery of caterpillars significantly impacted by Btk to pre-treatment levels required as much as two years.