Spider mites infest stressed garden plants and houseplants, especially in summer months. Control spider mites using natural organic pest control methods.
Several species of spider mites thrive in our gardens and on our houseplants, causing general plant decline for days or weeks before we detect their presence. Learn to recognize these tiny pests, and then use a combination of biological, spray, and cultural controls to eradicate them from your garden.
Spider mites are arachnids, so small they can barely be seen. But the damage caused by the piercing and sucking pests is apparent in the garden and greenhouse. Yellow or white stippling, red spots or yellow dots on the leaves are a warning that if the leaf is turned over the mite will be found amongst cast skins and bits of excrement.
The spider mite injects toxins into plant tissue while it feeds. The toxins cause discoloration along the veins, spreading to the entire leaf which will then dry out. Their attack keep plants from blooming, or the flowers could be disfigured. Bulbs are not safe from spider mites. An infestation can cause the bulbs to decay, turning them to dry pulp, inviting bacterial and fungal attacks.
Identifying Spider Mites
Spider mites have 4 pairs of legs, and the mouthparts are fashioned for piercing and sucking. The most common species of spider mites, cyclamen mite (Stenotarsonemus pallidus), the two spotted spider mite (Tetranychus urticae), and broad mite (Polyphagotarsonemus latus), can be found throughout the United States, as can the bulb mite (Rhizoglyphus echinopus).
Leaves and flowers of plants infested with spider mites might be encased in a fine webbing. A magnifying glass is needed to see the mite. To confirm their presence, tap a few leaves on a sheet of paper and watch for movement.
To the unaided eye, spider mites are nearly invisible, appearing as red, brown, or greenish dots as small as the period at the end of this sentence. As spider mites proliferate, the organic gardener can observe their damage, which occurs as brown or grayish leaves, which may appear speckled or drop off entirely.
Be suspicious of ailing plants with webbing, as sometimes unsuspecting gardeners mistake spider mite webbing for beneficial spider webs. If your spider mite problem has progressed to the point where you can see webbing encasing your plants’ leaves, the infestation is severe.
The Spider Mite Habitat
The spider mite thrives in dry, hot environments. Before bringing bedding plants into a garden or greenhouse, examine them carefully for mite damage. Once inside a greenhouse, the mite can crawl from one plant to another if they are placed close enough together so that the leaves touch.
Once the mite is introduced to the greenhouse, the conditions are perfect for rapid development from egg to adult. The hotter the conditions, the better for a new generation of mite to be produced every two weeks. The heat also encourages the number of eggs they lay.
A sun garden that has been treated with chemical pesticides is also inviting to the spider mite. Damsel mites, ladybugs, green lacewings and other types of mites that would be natural predators have been eliminated, making the garden safe for the mite while increasing its immunity to the very chemicals that target him.
Protect the Garden From Spider Mites
After the garden goes dormant in the fall, make a final inspection for the mite for evidence of damage. Don’t encourage spider mites to winter in your garden. Consider a dusting with diatomaceous earth for organic elimination of the garden pest.
Spider mites can catch rides around the property on garden tools or even on human hands. Keep rubbing alcohol available to clean tools, and don’t move from infected areas to mite free plants without a proper cleanup.
Trim yellow leaves or dried blossoms from plants with clean, sharp tools, and destroy the debris immediately. Keep the garden weed free, eliminating the formation of leave bridges the spider mite can use to travel from plant to plant.
Introduce wild brambles into an area near the garden, and keep them pesticide free to encourage firefly larvae, predatory midges, ladybugs, ambush bugs and dance flies who prey on the spider mite. If your garden has room, consider companion planting for natural pest control.
When planting bulbs for spring, inspect them carefully for corky brown spots or other signs of mite infestation. Destroy the bulb along with the infested soil around it. Don’t use infested debris for compost, and don’t plant fresh bulbs in infested areas.
Beneficial Insects
Several natural predators control spider mite populations, including ladybugs, pirate bugs, predatory thrips, and predatory mites.
You can purchase ladybugs or predatory mites from the Phytoseiidae family to release in your garden if your beneficial predator population is low.
If you have a hose-end attachment with a misting feature, use this in conjunction with the beneficial insect release to encourage your predators to remain in your garden.
Organic Dusts and Sprays
Spider mites are a member of the arachnid, or spider family, and as such require special sprays that target this family of pests. A common problem among gardeners using conventional pesticides is the use of chemical sprays that kill the beneficial predators of mites, but leave the pests untouched.
Organic gardeners can choose from horticultural oils, sulfur powder, or insect soap to control spider mites. If you choose horticultural oil, make sure you choose a lightweight summer formula, and not the viscous formula used as dormant oil.
Use insect soap with caution, as it can burn tender foliage in the hottest summer months that support mite outbreaks. Sulfur powder is a wise choice if your garden suffers from fungal diseases, as sulfur controls garden fungus as well as spider mites.
Cultural Control
Spider mites appreciate dry, dusty conditions, and they will exploit the stressed conditions of poorly irrigated plants by feeding on plant sap and relying on arid conditions to wick away their excretions. Dry weather also discourages beneficial insects, which allows spider mites to multiply unchecked.
If you notice the beginnings of spider mite webbing on your plants, blast them off with a strong jet of water from your rain wand.
Spider mite webs protect them from predators and function as a nursery for eggs, so blasting them away disrupts their life cycle. If your houseplants show evidence of a spider mite infestation, you can place them in the shower with you each day for a healing rinse.
