Beneficial Insects, Mites and Biological Control

Parasites tend to weaken individuals, and populations, and may make them more susceptable to other factors like disease. Predators, on the other hand, remove individuals from a population. Both help suppress pest populations. If pest numbers increase, a predator or parasite may respond to bring the numbers down. Predator numbers respond to an increase, or decrease, in the availablity of prey. These interactions are the basis for the field of insect ecology.

There are thousands of predatory and parasitic insects and mites. For gardeners the most important ones are lady beetles, syrphid flies, lacewings, predator mites and certain wasps.

common names and misnomers: ladybird beetles, lady bird beetles. ladybugs, hover flies

Natural enemies in your garden

The best sources of natural enemies for your garden are native plants in the area. Predators and parasites that migrate off native, natural areas into the garden are adapted to local conditions and will do the best job of pest control.

If possible, leave small areas of your landscape unmowed and untreated, and allow a natural succession of plants to develop. This may include some weedy species. These areas will serve as a natural enemy nursery for the rest of your landscape.

Also, avoid harsh insecticides that will wipe out beneficial species along with pests. What frequently happens is that pests return faster than natural enemies and the pest populations explode. Biorational insecticides have the smallest negative impact on beneficial species.