Despite your best efforts, pests can come out of nowhere even in your well-kept garden or houseplants. We need to know what’s attacking our plants with proper identification in order to take preventative measures. This week I discuss spider mites and whiteflies and how to control them. Last week, I discussed aphids and mealybugs.
What Are Spider Mites?
Eventually, a plant will become so weak it cannot grow, which will lead to stunted growth and deformed flowers. These pests feed on the sap, which also attracts ants, who swarm a plant infested with them.
Spider mites can be difficult to identify until the damage has already been done, since they are so tiny. If you suspect your plant has them, just put a piece of white paper beneath the leaves and tap, tap, tap. Then you can identify the speckles when they appear on the paper.
Spider mites aren’t completely different from spiders, as the mites prefer to rest on the undersides of leaves. You can tell that things are getting bad by finding yellowing, mottling and spotty leaves. The leaves may fall off and webbing may also be seen at the top of these plants if they have been infested with aphids before. By this stage, the plant is unable to be brought back to health.
Several years ago, I started out my horticultural career as an interior plant care technician in Boston, and they would suddenly appear once the heat was turned on. Many commercial clients had to have Dracaena marginatas, Bamboo Palms, Areca Palms, and Neanthe Bella Palms replaced because of bad infestations.
Whenever the weather changes, be sure to check your houseplants for spider mites. If you prefer to grow your own, keep an eye out for spider mites and thrips infesting pots.
How to identify spider mites
It is thought that spider mites are plant-eating mites that look like little spiders. In cool climates, they spend the winter resting in soil, but in warmer climates, they live and eat all year long. Spider mites feed on fluid extracted from plant cells with their needle-like mouth parts, most active in dry, hot conditions; they do not bite humans or pets, but they can harm indoor and outdoor plants.
The spider mite is a pest to more than 180 types of plants,1 so gardeners and indoor plant lovers are likely to encounter it sooner or later. A large variety of plants, many vegetables, fruits and herbs are susceptible to the mite.
Lacewing larvae, adult ladybugs, and other predatory insects present in the garden can reduce mite populations effectively. Growing plants indoors, especially in hydroponic systems (plants grown in water, not soil), increases the probability of spider mite infestations. Whether your problem is indoors or outdoors, recognizing the spider mites early on can preserve your plants’ health and prevent infestations.
It is difficult for the naked eye to see spider mites since they are so small. Females are larger, weighing less than one twentieth of an inch. These webs differentiate spider mites from other mite types as well as other microorganisms, like thrips and aphids, which can attack a plant. When spider mites are spotted and there are tiny holes visible in the foliage of the plant, spider mites are present and feeding.
You should check hydroponic and indoor plants at least once per month for signs of spider mites, before bringing them inside for the winter, and before planting landscape plants.
HOW TO CONTROL SPIDER MITES
For infestations of spider mites on outdoor plants, beneficial insects can help control spider mites, and mite populations large enough to cause visible plant damage require immediate attention. All types of plants can be treated with this product; on edible plants, it can be applied up to the day of harvest. For decorative plants and hydroponics kept indoors, treat plants outside with Insecticide and Miticide Ready to Use Spray. All products are derived naturally from chrysanthemum flowers and are effective on 250 different types of insects. Spray the top, bottom and side of your plants before you bring them in.
RELEASE PREDATORS LIKE LADYBUGS.
Release ladybugs or lacewings in your garden as a method of control. Lacewings devour soft-bodied insects much faster than do ladybugs. This obviously isn’t a viable solution for your houseplants! There is a predatory mite which control spider mites & a whitefly predator for the whiteflies. Both eat the eggs which is a good way to prevent future infestations.
SPRAY WITH WATER USING THE GARDEN HOSE, KITCHEN OR BATH SPRAY.
This is the method I fall back on. You want to gently blast off (no fire hose action here please) the pests & their eggs. The spray in your kitchen or bathroom will be suitable for your houseplants if you don’t have access to a hose outdoors. For these 2 pests, this method is a partial control. You’ll get the many of the adult spider mites & their eggs, but it’ll only work for getting the juvenile whiteflies & the eggs.
INSECT KILLER SPRAYS.
I don’t use chemicals so these listed are considered to be “natural controls”. They include: horticultural oil, insecticidal soap & need oil. Most plants can be sprayed with these but just check first. You can do a little research & see which would best for you.
HOMEMADE SPRAY RECIPES.
My favorite recipe for soap/oil spray is to mix 1 tablespoon mild dish soap with 1 tablespoon vegetable oil & 1 cup water. This works well for mild whiteflies even though the adults will fly away.
The following recipe has worked for me to control a mild spider mite infestation: Mix 1/8 cup apple cider vinegar (white vinegar will work) with 1 cup of water, 1/2 teaspoon baking soda, and a couple of drops of dish soap. It should only be used on and around established landscape plants and used as a deterrent.
STICKY TRAPS
It worked really well to get the adult whiteflies by hanging sticky yellow traps directly at the infested plants. The color yellow attracts whiteflies. They will fly right into the sticky traps.
How to deal with spider mite damage
Plants that are only severely damaged will recover quickly without special care, but those which are severely damaged will require additional attention. Be sure that all plants receive the necessary amount of sunlight for the variety. Keep the soil moist but not soggy and re-fertilize plants regularly, which gives plants a nutritional boost immediately. New, healthy leaves start developing on the plant; do not transplant or alter the plant’s environment.
In the early detection of spider mite infestations, you can resolve the issue more efficiently using Insecticide and Miticide, and even large infestations can be managed with a spray or dust.
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