Dear Aggie: I would like to use beneficial insects instead of insecticides. Where can I buy lady bugs to release?
Lady beetles (they are not bugs, but beetles) are predatory insects. They feed on nasty plant pests such as aphids, scale insects, and mealybugs. Unfortunately purchasing these insects and releasing them into the home garden is not very effective. They will not stay in one area and usually fly away quickly. It is better to employ strategies that conserve natural predators that are already present in your landscape. Anything you do to encourage lady beetles will also preserve other beneficial insects that are equally effective in controlling plant pests.
Ground beetles, praying mantids, dragonflies, hover flies, fireflies, antlions, and lacewings also feed on other insects. These predators are common in most healthy landscapes. Depending on the species, they feed on slugs, midges, gnats, mosquitos, aphids, ants, scales, mealybugs, thrips, and mites.
Parasitoid wasps are another group of insects that are important in controlling plant pests. Typically, they lay their eggs on or in another insect. Once the eggs hatch the host insect dies. These wasps range in length from ½-inch to 1/8-inch and they DO NOT sting people.
There are many things you can do to preserve these natural biological controls:
1. Do not use pesticides. Insecticides are not specific to insect pests — they kill all insects. This can upset the natural balance leading to fewer beneficial insects.
2. Provide a diversity of plant species, especially flowers. Many beneficial insects also feed on nectar and pollen. Include different plant sizes, deciduous and evergreen and different flower shapes and colors.
3. Provide shelter by allowing unkempt, natural areas to develop in your landscape. Leaf litter, brush and rotting logs provide not only shelter, but egg-laying and over-wintering sites. Create ‘no-mow’ areas to encourage insect diversity.
4. Learn to recognize beneficial insects. For example, the larvae of lady beetles are very strange looking. Many people kill them because they think they are some type of pest. The larvae are actually just as efficient as adult lady beetles in consuming plant insect pests.
The release of predatory insects can be effective if they are released into confined areas such as high tunnels or greenhouses. Lady beetles are commonly used to control pests in commercial greenhouses.
Mother Nature will keep things in balance — we just need to allow her to do her job!
Written by Sue Gwise, Cornell Cooperative Extension consumer horticulture educator.
