They are tiny but deadly ... to your garden, that is. We're talking about spider mites, minuscule members of the arachnid family with enormous appetites. Not to be confused with dust mites, these voracious pests, common throughout much of the world, will happily munch on any of 100 different species of plants. Here's how to stop them from eating -- and killing -- your fruit trees, berry bushes, veggies, flowers, and houseplants.
Signs of Spider Mite Infestation
Spider mites love hot weather and low humidity. This makes the signs of infestation easy to confuse with the effects of a dry spell. And in fact, the two problems are essentially the same; spider mites literally suck the juice out of greenery. Your plants will begin to appear scorched, with yellow flecks or edges. Should the infestation continue without treatment, they'll gradually turn gray and eventually die.
Oftentimes spider mites leave a more obvious clue to their presence, though -- a mesh of sillky fibers designed to protect the colony against predators, which resembles the webs spun by actual spiders. (That's where spider mites get their name ... and yes, the species are related.) If you see webbing on your plants, look out for spider mites. At less than 0.04 inch in length, they resemble tiny red, yellow, green, or black wriggly dots. The pests can be hard to spot with the naked eye, but will show up under inspection with a magnifying glass, especially if you check the underside of affected leaves.
Natural Treatment for Spider Mites
The main reason why spider mites are so prolific today is rather ironic -- large numbers of their natural predators were killed off by the use of pesticides. Reintroducing these predators (big-eyed bugs; stethorus, a type of lady beetle aptly known as the "spider mite destroyer," pirate bugs, and predatory thrips) may be useful as a garden pest control measure. The spider mites themselves reproduce rapidly and can quickly develop a resistance to chemical insecticide.
Removal of the mites' webbing might be somewhat helpful, as well, since they will not lay new eggs until they have spun replacement webs. At the same time, trim the plants carefully and discard heavily infested leaves and plants. Sad to say, these trimmings must not be put on your compost pile. Instead, place them in garbage bags, close tightly, and dump them in the trash, to prevent further spreading of the spider mites.
Once the plants have been trimmed, wipe down the leaves with a damp cloth or spray them with water, particularly the undersides. You may wish to add a few drops of liquid dish soap and/or essential oil to the water. Rosemary oil is considered highly efficacious, as are neem, chrysanthemum, thyme, and lemon oils.
We Tried It: Spraying Spider Mites with Essential Oil
My geraniums started out strongly this spring. Placed in a sunny outdoor window box, they graced the landscape with gorgeous color for a couple of weeks. Then they started to fade and wither rapidly. Opinions ranged from "not enough sun" to "too much sun" to "well, they've bloomed and now they're finished for this year."
As a relatively new gardener, I decided to trust my instincts and try to nurse them back to health. When I began removing the burnt-looking leaves, I noticed both the signature webbing and hordes of barely visible critters. I didn't have any of the aforementioned essences, but I did find a bottle of natural peppermint oil, bought in an attempt to ward off mice (I have a lively household!). I filled a spray bottle with water, a quarter teaspoon of dish liquid, and 5 or 6 drops of peppermint, and proceeded to spritz the leaves, top and bottom.
The immediate effect was that the air smelled delightful. And longer term? It's now a week since I sprayed the geraniums and the difference is amazing. They are mite-free, lively and lovely.
Laura Firszt writes for networx.com.