How to Get Rid of Spider Mites on Plants

Spider mites (Tetranychus urticae) are members of the Arachnida class and are often found in gardens, as they feed on many species of plants. Spider mites are less than a millimeter in length, making them difficult to spot, though they swarm in groups known as colonies. Spider mites can come in several colors—from red and green to yellow and brown. The two-spotted mite and red spider mite are among the most common types found on indoor plants and gardens. When the conditions are right, they can hatch in just three days and multiply from there.

Spider mites have a life cycle of only three to four weeks. In that time, females can lay hundreds of mite eggs. This population growth can cause spider mite infestations for indoor and outdoor plants. Colonies will cling to host plants, stymying their growth and making them more prone to diseases and other health issues. Spider mites will grasp the base of leaves and feed off their chlorophyll, stealing nutrients from entire plants.

These arachnids can be a nuisance, particularly in the spring and summertime, since hot and dry conditions reaching 80 degrees Fahrenheit will expedite hatching. After hatching, larvae can grow to become sexually mature in just five days.

Small as a grain of sand, a spider mite can be near invisible to the naked eye. Nonetheless, there are telltale signs of spider mites to help you spot them on infected plants:

• Use a magnifying glass. A magnifying glass can help you find small spider mites more easily. Check the underside of plant leaves and search for what may look like many grains of ground black pepper, red specks, or other dots in earthy hues. With a magnifying glass, you might see their ovular bodies and eight legs, or for two-spotted spider mites, you’ll see a dot on their front and back.
• Tap the leaves of your plant. Spider mites thrive on the undersides of leaves. Place a sheet of paper under a leaf, and gently pat the leaf. Use plain white paper so you can more readily see any mites that fall off the leaf.
• Identify plant damage. Predatory spider mites rely on plants for food, biting into green leaves with their sharp mouthparts and causing the parts of or entire plants to discolor or wilt. If your plants are gradually becoming yellowed or disfigured, they may have fallen prey to spider mites.
• Look for fine webbing. As their name suggests, spider mites spin webs like spiders for protection. Look for wispy white threads of webbing on the leaves of plants as a sign of spider mites.

Many spider mites are resistant to insecticide. Fortunately, there are a few all-natural, homemade miticides that can control spider mites. Try these pest control methods to combat the spread of spider mites quickly:

1. 1. Create a soap solution. Mixing liquid dish soap and water is a DIY way to take care of invasive spider mites as the soap will stick to and suffocate them. Combine one quart of lukewarm water with one teaspoon of liquid dish soap, shake the solution up, and pour it into a spray bottle. Periodically spray the underside of the leaves with the soap until the mites are gone.
2. 2. Use rubbing alcohol. Rubbing alcohol can work as another miticide that efficiently kills off predatory spider mites. Dab some onto a tissue or cotton ball, hold a leaf taut, and gently swipe the rubbing alcohol-wetted item over the leaf. This liquid will dehydrate and kill spider mites. A couple of hours later, use a garden hose to cast off the dead mites. If your plants are sensitive, you might want to dilute your rubbing alcohol. Use a one to three rubbing alcohol to water ratio, pour the mixture into a bottle, and spray the infested plants.
3. 3. Encourage beneficial predators. Pesticides don’t always work as a repellent on spider mites, but they work on other natural enemies that could help you keep the mites away. Such natural predators act as biological control by preying on spider mites. Insecticide-free gardens with mites might attract lacewings, thrips, ladybugs, and other beneficial insects.
4. 4. Use neem oil. This horticultural oil acts as a natural pesticide but isn’t toxic to pets, humans, or other animals. This natural extract suffocates spider mites, quickly killing them. Mix a tablespoon with water in a bottle, shake it up, and spray over the affected foliage. When using neem oil, be careful that it doesn’t get on clothing or furniture.
5. 5. Spray rosemary oil. Rosemary oil is pet-friendly and safe for humans but deadly for spider mites. Combine one teaspoon of rosemary oil with one quart of water and mix it up. Pour the solution into a spray bottle and spray the infested plants. Since rosemary oil is safe for humans and pets, this solution works well on fruit, vegetable, or houseplant pests.

After taking care of a spider mite infestation, it’s essential to tend to damaged plants to ensure they continue to thrive.

• Prune any affected leaves. A leaf may be too far gone to save. If this is the case, you are better off discarding the browned or disfigured foliage—this will keep the rest of your plant healthy, so nutrients aren’t wasted on the dying leaf. Put the leaf in a garbage bag and remove it from your house so the pests don’t return. Once the leaf is pruned, tend to the other surviving leaves as they may have also been infected.
• Isolate new plants. If you are suspicious that your garden or plants have been exposed to predatory mites, you’ll want to keep your other plants as far away as possible (while still keeping them in sunlit areas). Spider mites travel easily from plant to plant, so you’ll want to keep new plants or unexposed ones away from infected areas.
• Provide careful nourishment. After tending to damaged leaves, your plant will be more sensitive and need mindful care. Check if the soil is too dry or oversaturated to make sure it is getting the right amount of sunlight and water. Additionally, try not to move the plant or disturb its ecosystem so it can recover fully.

Grow your own garden with Ron Finley, the self-described "Gangster Gardener." Get the MasterClass Annual Membership and learn how to cultivate fresh herbs and vegetables, keep your house plants alive, and use compost to make your community—and the world—a better place.