Crop Management

Spider mites prefer hot, dry conditions. Frequent watering or misting of plants can help to prevent mite outbreaks. Spider mites frequently become resistant to insecticides; the application of nonselective insecticides may cause mite outbreaks by killing naturally-occurring mite predators. Severe spider mite infestations can be treated with products that are less toxic to predators, such as insecticidal soaps. Prevent spider mite outbreaks by scouting and applying biological controls as needed.


img3Spider mites have 4 pairs of legs, thus they are arachnids, not insects. They are susceptible to miticides more than insecticides. The most common species in interior environments is the two spotted spider mite, Tetranychus urticae. With a hand lens, two lateral spots on the body and red eye spots may be seen. Mites puncture cells and suck up cell contents, causing spotting or stippling of leaves. They are found first on the undersides of leaves, sometimes with silken webbing.

Typical damage symptoms are small yellowish flecks resulting from mites feeding on leaves. As mite populations increase, areas infected increase. In severe cases, whole leaves appear pale or ghostlike. To prevent such a damaging build-up, plants should be inspected regularly for the presence of mites. Inspect once weekly in the winter and twice weekly in the summer, if possible. Look at undersides of leaves with a 10X hand lens in several locations. Introduce mite predators as soon as mites are observed.

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