Common names: Spider Mite, Twospotted Spider Mite, Red Spider Mite
Scientific name: Order Acari, family Tetranychidae, Tetranychus urticae
Size: Adult--1/150" to 1/50"
Identification: Adults are reddish brown and spiderlike with eight legs; no antennae, thorax, or wings. Eggs are laid at the base of plants or on the plants.
Biology and life cycle: Many generations a year; the life cycle lasts only a few days. Adults hibernate in winter in debris or in bark.
Habitat: Many plants such as fruit trees, vegetables, ornamental plants, and house plants, especially stressed plants. Like dry climates. Spider mites like to overwinter in poke, Jerusalem oak, Jimson weed, and other weeds.
Feeding habits: Both nymphs and adults pierce plant cells and suck juice. Feed on fruit, foliage, and roots. Infested leaves turn silvery or yellow, then curl and are covered with a fine web.
Economic importance: Serious damage to food crops and ornamentals.
Natural control: Predatory spider mites, ladybugs, minute pirate bugs, thrips and lacewings, and lady beetles. Address the cause of the plant stress. Mites attack only sick plants.
Organic control: Spraying just about anything every three days for nine days will get rid of them. Garlic-pepper tea and seaweed mix is one of the best sprays. Citrus oil sprays are also effective.
Insight: Organic gardeners rarely have spider mite problems because of healthy soil, mulch, and adapted plants that have been planted properly. They are a problem only when soil is too wet or too dry.
Q: What can I use to rid my shrubs of "spider-mites" ?. The shrubs are covered with light (and unsightly) spider webs. I prefer not to use pesticides. C.S, Dallas.
A: Spider mite infestation is a clear sign that water is not effectively moving into the plant. The problem can be caused by too much or too little water, chemically imbalanced soil, compacted soil or other environmental issues. Liquid seaweed spray is highly effective to rid plants of spider mites, in fact it works as well or better than any of the toxic chemicals that are commonly recommended. However, the mites will re-infest unless the major problem that invited them in the first place is not corrected.