Establish Natural Defenses
A good long-term pest insect defense is to improve the soil in your yard by adding organic matter to it. Do this with mulch. Spread a 2 to 4 inch layer of organic material such as chopped leaves, grass clippings, compost, hay, shredded paper or straw either alone or mixed with peat moss 6 75 100 over bare soil all season long. As the mulch slowly decomposes it contributes vital nutrients to the soil and improves its structure and drainage.
Mites prefer dry, hot conditions. When you use organic material to mulch your plants, you create a situation that discourages them. First you create a sanctuary for many of the beneficial insects that prey on mites and their eggs. Second, the mulch retains soil moisture. A well-watered plant has a natural humidity in and around its leaf canopy which discourages mites. Mulching houseplants may not be practical, but setting pots on humidity trays helps maintain humidity. Fill a dish or tray with gravel and add water to just below the top level of the gravel, then set your plants on the bed of moist gravel to discourage mites.
Besides building rich soil, encourage the many insects and animals that normally prey on insect pests by planting lots of different kinds of plants. The natural predators of pest insects come in all shapes and sizes. Some are insects themselves, while others are microscopic organisms, amphibians, or birds. The more of these different kinds of predators that live in your yard, the fewer pest insect problems you will have. They will take up residence in a yard that includes their favorite plants and other foods. The greater the variety of plants on your property, the greater will be the diversity of natural enemies of pest insects that will be attracted to it and protect it.
Other Conditions That Foster Mites
Various kinds of birds and beneficial insects living in healthy home landscapes which host a diversity of plants and wildlife normally control local mite populations. However, frequent use of broad-spectrum insecticides also destroys beneficial insects. Outdoor plants repeatedly sprayed with these pesticides are most likely to develop bad spider mite infestations, because pest populations rebound faster than beneficials do, and the mites can establish themselves unmolested. Indoors, of course, there are no beneficial predators of mites, so they tend to be a chronic problem.
Mites also thrive in hot, dry conditions typical of summer in many regions and over-heated homes in winter. The hotter it is, the more rapidly they develop from egg to adult and the more eggs they lay. Left untreated a few mites on a plant can multiply to about 13 million mites in a month! Under ideal conditions, they quickly overwhelm a host plant and then begin to seek new hosts. They crawl from leaf to leaf, dangle from silk web strands until the wind blows them to a new plant, or they are carried on other insects, people, garden tools or water droplets to nearby healthy plants. PREVENTING MITES NEXT YEAR
Keep Trees, Shrubs, and Plants Vigorous
Unless the underlying stress that made your plants vulnerable to mite attack is identified and corrected, the pests may return next year. Give some thought to the affected plant’s situation. Make an effort to improve its vigor by watering it during dry periods over the summer and fertilizing it in the fall, if appropriate. Prune any injured or broken branches or stems cleanly and carefully. Mulch it to discourage weeds, hold soil moisture, and improve the health of its soil. Make sure the plant is getting enough light as neighboring plants may grow and block the sun over time.
Spray Horticultural Oil During The Winter
In late fall through early spring, before the new foliage begins to emerge on deciduous trees and shrubs, spray heavy horticultural oil (also called dormant oil or Volck oil) on their bark to suffocate any overwintering mites and their eggs. Be sure to coat all the bare limbs, trunks and twigs of each plant. This is especially important on fruit trees. Do not use this spray on anything but deciduous woody plants--ones that lose their leaves in the fall (avoid using oil on evergreens). Do not spray heavy oil if any leaf or flower buds are starting to swell. Always read and follow the instructions on the label of the product package.
Attract Beneficial Insects to the Yard
Birds, spiders, and predator insects kill many more mites than homeowners with insecticides do. Yards where broad-spectrum insecticides are not used host lots of beneficial insects such as minute bugs, pirate bugs, big-eyed bugs, damsel bugs, lady bug larvae, green lacewing larvae, and assassin bugs. All are predators of mites. To increase their numbers when mites become a problem buy beneficials from mail-order suppliers. Properly introduced into the yard, they will search out and feed on the mites and other pests as well.
Encourage the natural predators of mites to stay in your yard by providing them with a tempting variety of their favorite plant sources of pollen and nectar. Wild brambles are a nursery for beneficial bugs. The beneficials that prey on spider mites in orchards are particularly plentiful where blackberries are growing nearby. Hedgerows, windbreaks, and wooded patches also nurture beneficials that control mites on apple and other fruit trees. Border Patrolä is a seed mix of wildflowers that are particularly attractive to beneficial insects. Create an insectary by planting a patch of these flowers somewhere on your property.
Feed Birds Year Round
Next to beneficial insects, songbirds consume the most pest insects in your yard. Even seed-eating birds such as sparrows and finches seek insects to feed their young, sometimes as many as 3 broods of 3 to 4 babies a season.