What and when do I apply to crepe myrtles to prevent aphid damage?
Answer: Aphids overwinter as eggs and emerge in the spring, and continue to reproduce all season. They reach maturity in about 10 days, which makes for several generations each growing season. Because of their rapid life cycle, they are difficult to control with insecticides. Several species of predatory insects will feed on aphids, including ladybugs, green lacewings, and parasitic wasps.Using insecticides will harm the good insects along with the bad, so spraying all season is seldom beneficial or economical. However, if you have an infestation and want to spray, I recommend a least-toxic pesticide such as insecticidal soap, horticultural oil, pyrethrins, or neem oil. A good source of information for least toxic and organic approved pesticides can be found in ATTRA’s Biorationals: Ecological Pest Management Database.Another useful resource is the ATTRA tipsheet Aphids ? Botanical Control Formulations, which discusses the use of garlic, rosemary, papaya leaves, and mint to control aphids. Its references list can lead you to additional sources of information on this topic.