Spider mites might be tiny arachnids, but large populations can make plants look unhealthy and unattractive. The pests suck out plant juices with their needlelike mouthparts, causing a speckled appearance known as stippling. Affected leaves often turn yellow before turning brown or falling from the plant. If you peek beneath the leaves, you might even spot their trademark fine webbing. Traditional pesticides work on spider mites, but they also release toxins into the environment. Rubbing alcohol treatments can help you get rid of the mites without using potentially hazardous chemicals.
Rubbing Alcohol Treatments
Rubbing alcohol dissolves a spider mite's protective coating, which causes death by dessication. Dip a cotton ball or soft, clean rag into 70 percent isopropyl alcohol and wipe it over entire leaf surfaces, making sure you get it into all of the crevices and folds. Pay close attention to the undersides of leaves, where the pests like to feed, and wipe along leaf veins and edges as well. Wait about three hours after application to rinse the alcohol from the foliage. Rubbing alcohol doesn't affect spider mite eggs, so repeat treatments every seven to 10 days to remove newly hatched pests. Make sure the plant has been thoroughly watered before the application.
Alcohol Soap Spray
Alcohol sprays can kill spider mites, but you need to add a little soap to the solution to help it spread evenly and stick to the foliage. The experts at Mother Earth News recommend mixing 1 cup of rubbing alcohol and 1 teaspoon of mild liquid dish soap in 1 quart of water. Pour the solution into a handheld spray bottle and cover the tops and undersides of leaves as well as the stems. If the mites infect a small container plant, take a firm hold of the soil ball, turn the plant upside down and dip just the foliage into a bucket containing the alcohol and soap solution. Carefully swirl the leaves around in the liquid so the solution reaches all plant tissue. Repeat spraying or dipping every seven days until no more mites plague your plant.
Although an affective spider mite killer, rubbing alcohol can burn the leaves of sensitive plants. Test the solution on a few leaves and let it stand overnight. Treat your entire plant only if no damage occurs. Avoid treating plants that will be standing in direct sunlight after an alcohol application. The plants need to remain in a shady condition for at least three hours after an application so the foliage isn't damaged. As a precaution, treat outdoor plants on cool, overcast days or in the early evening hours. Allow container plants to thoroughly dry in a shady location before moving them back to their original spots.
Wearing waterproof gloves when handling alcohol solutions can help prevent skin irritation. If treating outdoor plants on a breezy day, wear goggles and a face mask as well.
Preventing Spider Mites
Spider mites thrive in dusty conditions, so regularly rinse off foliage with water from a garden hose or shower head to keep the leaves clean. As a bonus, the water rinses pesky spider mites off the leaves. Isolating new plants for at least 30 days gives you a chance to find out if they're hosting spider mites before you put them with your healthy plants. In addition, isolate infested container plants to keep spider mites from spreading. Keep enough space around plants that spider mites can't simply crawl from one plant to another.