Two-spotted spider mites are widely distributed in the United States and Canada and feed on over 180 host plants. Once a plant is infested, the mites spread on to nearby crops and ornamentals. Two-spotted spider mites pierce the epidermis of the host plant leaf with their sharp, slender mouth parts. When they extract the sap, the tissue of the leaf collapses in the area of the puncture. Soon a spot without green color forms at each feeding site. After a heavy attack, an entire plant may become yellow, bronzed or killed completely. The mites may spin so much webbing that it becomes entirely covered.

Though insects and mites are in a group called the Arthropoda {meaning jointed foot}, because jointed legs are common to both, spider mites are not actually insects. Being more closely related to spiders, they derive their name from the thin web that some species spin.

Two-spotted spider mites overwinter as adults in the soil or on hosts such as violets and hollyhocks. In mild winter weather, two-spotted spider mites continue to feed and lay eggs, although development in the winter is much slower than in the summer. In warm weather, six legged larvae hatch from the eggs. They develop into eight-legged nymphs, which pass through two nymphal stages.After each larval and nymphal stage, there is a resting stage. The adults mate soon after emerging from the last resting stage, and in warm weather the females soon lay eggs.

Mites can be identified by shaking symptomatic leaves on to a sheet of white paper or by observing infected leaf areas with a hand lens.In hot dry temperature, mites can cause plants to drop leaves in a few weeks.Fruit from severely infected plants are often unmarketable because defoliated plants tend to yield small, poor quality fruit.

The eight-legged female mites are yellow to dark green with two to four dark dorsal spots. At 1/60 of an inch, they are almost microscopic. Males are smaller with more pointed abdomens. The tiny, spherical, eggs are laid on the undersides of leaves, often under the webbing produced by the mites. A six-legged, colorless larva that emerges resembles the nymph and adult, but is only the size of an egg. Both of the eight-legged nymphal stages look like the adult, but are smaller and not sexually mature. Under optimum conditions of high temperature and low humidity, the life cycle may be completed in 3 days. Females can lay 200 eggs.

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