Pyrethrum Aerosol for Spider Mites

Spider mites are small pests that can be treated with pyrethrum aerosols.

Spider mites are a common pest of a wide variety of plants grown in the home garden as well as indoors. Spider mites are a member of the arachnid class of animals along with ticks and spiders. Spider mites live in colonies and can quickly damage plants if left untreated. Pyrethrum aerosols, while not the most effective treatment for managing spider mites, can provide a temporary solution for removing spider mites from infested plants.

Pyrethrum

Pyrethrum is a synthetic pesticide that is commonly sold as an aerosol application. Pyrethrum is the most widely used pesticide in the United States, according to Colorado State University. The active ingredient of the pesticide, pyrethrin, is derived from chrysanthemums and, while highly effective at killing garden pests such as spider mites, is nontoxic to mammals, making it one of the safest pesticides on the market.

Spider Mite Damage

Spider mites are small insects that can be difficult to spot to the unaided eye. The largest species only grow to 1/20 inch in size. However, plants infested with spider mite colonies will display several symptoms. Mites cause damage to garden plants by feeding on nutrients in the leaves of the plants. Small numbers of spider mites may cause bronze spots to appear on leaves. If left untreated, spider mite populations quickly increase and can cause entire leaves to turn yellow and drop off the plant. Garden plants with severe spider mite infestations are often covered with a fine web and should be treated with a pyrethrum aerosol.

Pesticide Problems

Spider mites most commonly become a problem in home gardens after applying a broad spectrum pesticide. Such pesticides kill off the natural predators that control spider mite populations. Garden insects such as lacewings, lady beetles, thrips and predatory mites feed on spider mites and protect garden plants. In addition, traditional pesticides such a carbaryl, organophosphates and high concentrations of pyrethrums -- found in liquid and granular forms of the insecticide -- can actually increase the reproduction rate of spider mites, according to the University of California.

Application

Pyrethrum aerosols should only be applied on plants that have severe spider mite infestations. Since pyrethrum is a nonselective pesticide, it will kill beneficial insects in your landscape as well as spider mites, which can complicate your pest problems. Applying pyrethrum aerosols to select areas of plants to kill high concentrations of spider mites is the best way to utilize the pesticide sprays. Follow-up treatments with insecticidal soaps and thorough husbandry will help prevent future spider mite damage on your garden plants.

References

• University of California Integrate Pest Management Program: Pests in Gardens and Landscapes: Spider Mites
• Colorado State University: Some Pesticides Permitted in Organic Gardening; Laura Pickett Pottorff
• Ohio State University Extension Fact Sheet: Spider Mites and Their Control; David J. Shetlar
• Texas A&M University: Spider Mite