One of the great things about living in our century is that there are pest-control products available that are non-toxic for you and your family. Horticultural oil is one of them. It’s a safe, time-tested practice that’s been around far longer than today’s strong pesticides.
Horticultural oils are comprised of certain oils that are mixed with an emulsifying agent. When combined with water, they can be sprayed to control lawn and garden pests such as aphids, mites, scale insects, whiteflies, and others.
There are two kinds of horticultural oil. Dormant oils are used on woody plants during the dormant season. Summer (or folar) oils are applied during the growing season, when your plants have foliage. There’s no chance that horticultural oils can lead to insect resistance, because they work by dehydrating and/or suffocating insects and their eggs.
On the other hand, for the safety of your plants, horticultural oils must be sprayed only at certain times and in certain amounts. Otherwise, you risk injuring your plants. Some plants are more sensitive than others.
Our illustration, which is an 1897 line drawing entitled Cryptorhynchus lapathi (a Willow pest) is from the Library of Congress. The original caption: 1. Beetle 2. Section of infested wood 3. Larva 4. Pupa (dorsal view) 5. Pupa (side view)