They are called spider mites because they have eight legs and can make webs, although larvae only have six legs. They are not spiders but are arachnids. Gardeners sometimes call them webspinning mites.
No matter what you call them, all of the species eat plants and covers plants with thick webbing. They can soon decimate a garden, especially in times of little rain. They love hot, dusty conditions. Males die off in winter but females can hibernate.
Spider mites are incredibly small — only about 1/50th of an inch to 1/20th of an inch long. They resemble moving dark dots that can barely be seen by the naked eye. They have red eyespots. Females are larger than males and sport dark spots on the sides of their bodies. One spider mite is nearly impossible to see. But spider mites live in colonies, which moves over plants and sidewalks like a river of tiny jelly beans.
The damage they do to plants is easily visible. Leaves first appear stippled, or covered in tiny pale dots. As feeding continues, leaves gradually turn grey or bronze and the plant can die. Webbing appears on the plants, on leaves and in between leaves.
Fortunately, there are many ways a gardener can greatly reduce or eliminate spider mite infestations. Neem oil can be used to kill spider mites, according to The Organic Gardener’s Handbook of Natural Insect and Disease Control (Rodale, 1996). Mix anywhere from 1 to 4% with water and spray the affected plants. Mites die from direct contact with the oil. Repeat every one to two weeks.
Another option is making an insecticidal soap spray. Mix 2 parts of insecticide soap per gallon of water and spray directly onto plants. Rinse the plants off after a half hour.
Some gardeners prefer to use predatory mites to get rid of their spider mite problem. However, the University of California notes that in order to be effective, a gardener needs one predatory mite for every ten spider mites.
Never use carbaryl insecticide on spider mites. According to the University of California, it is completely ineffective against spider mites. Other undiluted broad spectrum commercial insecticides can kill adult spider mites, but also kills off insects that feed on spider mites, such as ladybugs and lacewings. However, commercial insecticides cannot kill spider mite eggs. By the time they hatch, the effects of the pesticides are often gone.
This can set up a deadly cycle for the gardener who relies only on pesticides for mite control. When spider mite eggs hatch, there are no predators to kill the next generation. This causes a population explosion in spider mite colonies.
- · The Organic Gardener’s Handbook of Natural Insect and Disease Control. Barbara W. Ellis, et al. Rodale; 1996.
- · University of California Integrated Pest Management Program. “Spider Mites.” L. D. Godfrey, December, 2011.
- · Ohio State University. “Spider Mites and Their Control.” David J. Shetlar. 2011.