Various pesticides are readily available to home gardeners for use in controlling spider mites. Unfortunately, many of these pesticides cause more harm than good. For example, over use of chemically filled insecticides can disrupt the life cycle of beneficial insects that keep garden pests -- such as spider mites -- under control. Without these beneficial insects, the number of spider mites begins to increase leading to a full-blown infestation. Safer options are available that won’t cause harm to you, your family or beneficial insects.
1. Soap Pesticides
Containing nontoxic fatty acid, insecticidal soap is one of the safest options for gardeners looking to control soft-bodied insects. This contact insecticide dissipates in the environment rather quickly so it doesn’t leave any residue on your plants. However, the spider mites must encounter the soap pesticide for this option to be effective. Even though insecticidal soap is readily available at home improvement stores and garden centers, you can create your own soap pesticide to control spider mites with a few common household items. Simply mix 1 tablespoon of gentle soap that doesn’t contain fragrances or dyes -- such as Castile soap -- with 1 quart of soft water. Apply this homemade solution to the infested plant, covering the entire leaf surface including the underside of the foliage.
2. Oil Pesticides
Commercially available horticultural oil contains highly refined petroleum that -- when it encounters the pest -- will smother it. Since oil pesticides decay rapidly in the environment, they pose little risk to beneficial insects. Another option is to create your own homemade oil insecticide using the same cooking oil sitting in your kitchen pantry. Merely combine 1 tablespoon of freshly opened cooking oil, 1 tablespoon of baby oil and 1/2 gallon of soft water. Cover the foliage with the homemade oil spray and repeat 5 to 7 days as needed. Oil pesticides should never be used on plants with hairy or waxy leaves as it may damage the plant.
3. Plant-Based Pesticides
Plant-based pesticides contain ingredients derived from plants and are generally considered safer than pesticides filled with harsh and dangerous chemicals. Neem oil is a popular choice for gardeners looking to control pests organically. Not only will it kill various garden pests -- such as spider mites, thrips and whiteflies -- it will control fungal diseases including powdery mildew and scab. Neem oil is nontoxic to mammals and people, and has a very low toxicity level to beneficial insects. It can, however, harm bees so only apply at times when bees are not present. Unless the neem oil is ready-to-use, it will require mixing with soft water at a rate of 2 tablespoons of oil for every gallon of water.
Care must be taken with what type of pesticide you choose. Carbaryl-containing insecticides, for example, will stimulate the reproduction rate of spider mites leading to a worse infestation than when you started. Furthermore, always follow the specific directions and warnings designed for the type of pesticide you use to control spider mites. Another option to keeping spider mites at bay is to ensure your plants are receiving proper care with good irrigation, fertilization and sanitation practices.
- University of California Statewide Integrated Pest Management Program: Spider Mites
- Colorado State University Extension: Spider Mites
- Horticulture: Mix Your Own Insecticidal Soap for Garden Pests
- University of California Agriculture and Natural Resources: Using Horticultural Oil Spray
- University of Florida IFAS Extension: Home Remedies for Insect and Disease Control on Plants
- University of California Statewide Integrated Pest Management Program: Neem Oil
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