Beneficial Insects to Buy for Your Garden

Harmful insects can do a lot of damage to your garden. If you are like me and refuse to resort to using chemicals that can also harm the environment, you will want to find more natural, more organic methods of insect control. There are two insects that you might want to consider purchasing if your garden is being attacked by large numbers of pests, and there seems to be no natural predators helping to control their populations. Both of these insects can be purchased from a farm supply company or from any number of online companies. The two particular insects to consider adding to your garden are trichogramma wasps and nematodes.

Trichogramma Wasps
These extremely tiny insects - one millimeter or less in length or less - have been used by gardeners and farmers for years to control numerous garden pests. (They also do not sting humans.) These pests include: corn earworms, cutworms, cabbage loopers, codling moths, and tomato hornworms. (Trichogramma wasps actually prey upon over 200 different species of harmful insects.) The adult wasp lays its eggs inside the eggs of a host, where the wasp larvae eat the contents. The host eggs then turn black as the wasps mature. This breaks the reproductive cycle of the host insect, essentially preventing the larvae from morphing into adults that can reproduce and harm your plants. The tiny little wasp then flies off to find other hosts in which to lay eggs.

Nematodes
Nematodes are very tiny little roundworms that live in the soil and feed on a variety of pests, such as artichoke plume moths, armyworms, cutworms, cranberry girdler, fungus gnats, root weevils, wireworms, and white grubs. Not all nematodes are beneficial, however. (Some species can actually do a great deal of damage to your garden plants and trees.) This means that you should specifically look for the nematodes known as entomopathogenic nematodes, specifically the genera Heterorhabditis and Steinernema. These are usually purchased in small containers, which contain millions of nematodes.

To release your nematodes, rake back any mulch, ground cover, or thatch from the area in which they are to be released. Thoroughly water the area, making it as wet as possible. Follow the instructions on the container and mix the nematodes with water. Apply according to the instructions using a watering can. The best time to do this is in the evening, because hot sun and dry air can kill your nematodes.

All gardens have beneficial insects, including the two described here. Usually there is no real need for the average gardener to buy extras. However, if you have killed off most of your beneficial insects through the overuse of harsh chemicals in an effort to rid your landscape of harmful pests, you may find it necessary to reintroduce beneficials to your landscape/gardens. Before you do, however, discontinue the use of those harsh chemicals, which tend do more harm to the beneficials than to the pests.

References:
National Sustainable Agriculture Information Service. Entomology: Beneficial and Predatory Allies.

Buglogical Control Systems. Trichogramma Egg Wasps - Trichogramma sp.

Cornell University/Biological Control: A Guide to Natural Enemies in North America. Nematodes (Rhabditida: Steinernematidae & Heterorhabditidae). Randy Gaugler.

Janet Marinelli, ed. Natural Insect Control: The Ecological Gardener's Guide to Foiling Pests. Brooklyn, NY: Brooklyn Botanic Garden, Inc., 1994.