Another type of Bt is active against leaf feeding beetles, including the Colorado potato beetle and the bean leaf beetle. In all cases Bt is more effective against young insects than older ones. Monitor your plants frequently so you'll know when the insects are just hatching from their eggs and are most susceptible, and make applications at that time. As a last resort, use selective insecticides as spot treatments when other options are not available or when they have failed to provide adequate control. The home gardener has two environmentally friendly spray options for many insect pests, insecticidal soap products and oil sprays.
Soaps act selectively on many pests including aphids, squash bug nymphs, leafhoppers, and thrips.
These soaps break down quickly and do not cause any long term environmental contamination. Due to the selective action of these products, beneficial insects are not harmed by soap sprays. Oil sprays act to suffocate insect pests, and also have the advantage of rapid breakdown. These compounds are not toxic to humans and will not cause environmental contamination. However, they are not selective in their action, so overuse may have detrimental effects on beneficial insect species.