So don't forget to include water in your least toxic program. This microbial insecticide revolutionized pest control methods in the 1970s when it first became widely available to home gardeners. It kills only moth and butterfly larvae and is harmless to most other insects and animals. However, don't spray throughout the garden or excessively. It won't discriminate between pest caterpillars and those of desirable moths and butterflies.
Many types are available from various manufacturers.
Don't use horticultural oils when you expect temperatures to rise above 90 o F. 4. These specially formulated soaps are a key element in any least toxic pest-control strategy. They are effective against a wide range of mite and insect pests, particularly soft-bodied insects such as aphids, immature scale, leafhoppers, mites, thrips, and whiteflies. Soaps are essentially nontoxic to humans and wildlife, but they can damage some plants, especially ones with dull leaf surfaces or many leaf hairs. Luckily, few roses fall into those categories.