What Are Predatory Mites?

Under the Magnifying Glass

• Mites are nearly invisible to the naked eye -- they're only 1/50 inch in diameter -- but you can see them moving on a plant leaf if you use a magnifying glass. Adult predatory mites have pear- or teardrop-shaped bodies and eight legs. They come in a variety of colors, including cream, green and red, depending on the color of their most recent food source. They lay clear, oval eggs in clusters on the undersides of leaves, and the eggs hatch within a few days and go through a six-legged larval stage before becoming eight-legged nymphs.

Helping Your Plants

• Although predatory mites live and breed on plants, they do not feed on or harm foliage or flowers. Instead, they hunt and devour pest mites, such as spider mites, and other small insect pests that feed on plants. When prey mite populations are low, predatory mites instead feed on plant pollen -- they will not turn on the plants and harm them. Although most predatory mites thrive in humid greenhouse conditions, some varieties can also thrive in hot, dry summer garden beds.

Release the Mites

• Predatory mites are often naturally present in small numbers in most garden beds, but you can increase these numbers by buying and releasing predatory mites when pest mite numbers are high. Choose a type of mite that is native to your area to ensure the mites can thrive in the temperature and moisture conditions in your climate. The mites come packaged in a bedding material, usually vermiculite or sawdust. Spray the soil around the infested plants lightly with water to provide a moist environment. Place the bedding material, which contains the mites, in a shaker container and sprinkle them over the moist soil in the morning or evening when temperatures are lower.

Insecticide Warning

• Broad spectrum insecticides kill predatory mites, along with the pests. If you want to increase the amount of predators in the garden, avoid using insecticides when possible. If you must use an insecticide, mix 1 tablespoon of insecticidal soap with 1 quart of water and spray the plants two or three days before introducing the predators. The insecticidal soap kills mites on contact, but it doesn't stay on the plant so it won't harm the predators when you release them a few days later.