To the naked eye, these tiny spider relatives look like red, green, or yellow flecks on foliage. They are especially prevalent in inland areas with warm summers, where they attack a wide variety of trees, shrubs, and vines. Leaves of infested plants turn yellow and may be covered with fine webbing. To confirm a diagnosis, hold a piece of white paper below leaves and tap them. If mites are present, they'll drop onto the paper and look like so many rapidly moving specks.

Wash mites off plants with strong blasts of water, then follow up with soap spray. Any dust that settles on plants in late summer encourages mites, and they also prefer dry air, so regular rinsing of leaves with water is an excellent control. Summer oil and sulfur will also control spider mites, but do not use them together; they are toxic to plants in combination. If you first use one, don't use the other for 1 month.

Chemical controls are not recommended.