It can be scary to discover that one of your favorite plants is suffering from a pest infestation. Luckily, in most cases, your plants can be saved with relatively little effort! Always isolate a plant as soon as you notice pests, check your other plants, and clean the surrounding area with disinfectant. Here are a few of the most common types of indoor plant pests along with information on how to recognize and get rid of them. 
These indoor plant pests are typically green, white, or black, and about 3 mm long. They suck sap out of plants near areas where new growth is appearing. Your plant’s leaves can turn yellow and fall off or new growth may appear deformed and stunted Aphids often come in on plants that were grown or kept outdoors, so be sure to check plants before you bring them inside for winter. They have a symbiotic relationship with ants, so they can also come in along with an ant infestation. Ants “farm” aphids in order to eat a sugary substance they produce while feeding on plants. Once you notice aphids, you’ll want to act quickly to remove them, as they can multiply in less than a week and may travel to other plants. 
These white fuzzy bugs can grow to be up to ¼ inch long, and suck sap from new growth causing leaves to die and fall off. They create a sweet secretion known as “honeydew” which can leave plants vulnerable to infection by fungus or mold. Citrus trees, tropical houseplants, and overwatered houseplants are particularly susceptible to mealy bugs. These indoor plant pests commonly come into the house on new plants that were grown in greenhouses, where the environment is warm and humid. Mealy bugs can asexually reproduce, so even one bug left on a plant can cause an entire infestation. 
While scale may look more like a disease, it is actually a type of insect that does not move once it reaches maturity and latches onto a plant to drink sap. It typically appears as brown raised patches resembling scales, but can also be almost any other color. Symptoms include sticky residue on the leaves and stems of a plant, or yellow and deformed leaves. Scale insects commonly come inside on cut flowers, produce from farmers’ markets or grocery stores. An infestation can also be spread by a new plant from a garden store or nursery, or outdoors. Scale can even survive in used potting soil until it comes into contact with a new plant. 
These tiny arachnids can be white, brown, or red, but are almost invisible. You probably won’t know they’ve attacked your plants until you see fine dense webbing around the edges of the leaves and stems. Symptoms of spider mite damage include brown and yellow speckled leaf discoloration, or extreme cases, yellow or dying leaves. Spider mites thrive in dry conditions, so under watered plants are more susceptible. They can become even more of a problem in the winter when humidity levels drop indoors. 
Aphids
These indoor plant pests are typically green, white, or black, and about 3 mm long. They suck sap out of plants near areas where new growth is appearing. Your plant’s leaves can turn yellow and fall off or new growth may appear deformed and stunted Aphids often come in on plants that were grown or kept outdoors, so be sure to check plants before you bring them inside for winter. They have a symbiotic relationship with ants, so they can also come in along with an ant infestation. Ants “farm” aphids in order to eat a sugary substance they produce while feeding on plants. Once you notice aphids, you’ll want to act quickly to remove them, as they can multiply in less than a week and may travel to other plants. Treatment:
- Wash off as many aphids as possible with lukewarm water from a shower or sink sprayer. Then, spray the leaves with a mixture of 5 drops of dish soap to about a liter of water. Be sure to first check online to make sure your plant isn’t sensitive to soap, or try a bit on one leaf first to test for a bad reaction.
- You may also want to try applying neem oil spray, which can be bought at most plant stores, hardware stores or online. Do not place a plant in direct sun soon after using neem oil as this could cause leaves to burn.
- If you’re willing to put in a bit more time, you can dip a Q-tip rubbing alcohol and swab the aphids with it to kill them instantly.
Mealybugs
These white fuzzy bugs can grow to be up to ¼ inch long, and suck sap from new growth causing leaves to die and fall off. They create a sweet secretion known as “honeydew” which can leave plants vulnerable to infection by fungus or mold. Citrus trees, tropical houseplants, and overwatered houseplants are particularly susceptible to mealy bugs. These indoor plant pests commonly come into the house on new plants that were grown in greenhouses, where the environment is warm and humid. Mealy bugs can asexually reproduce, so even one bug left on a plant can cause an entire infestation. Treatment:
- Reduce watering as much as you can without harming the affected plant.
- Drop the temperature below 60 degrees for cold tolerant plants. This can be done by adjusting the night setting on your thermostat, or placing the plant in a cool basement room, as long as it still has a light source.
- Wash leaves with warm water, or, for studier plants, use a garden hose to dislodge the bugs.
- Polish leaves with neem oil
Scale
While scale may look more like a disease, it is actually a type of insect that does not move once it reaches maturity and latches onto a plant to drink sap. It typically appears as brown raised patches resembling scales, but can also be almost any other color. Symptoms include sticky residue on the leaves and stems of a plant, or yellow and deformed leaves. Scale insects commonly come inside on cut flowers, produce from farmers’ markets or grocery stores. An infestation can also be spread by a new plant from a garden store or nursery, or outdoors. Scale can even survive in used potting soil until it comes into contact with a new plant. Treatment:
- These insects have a touch outer shell that makes them resistant to most pesticides, so chemical treatments are not a good option
- One way to get rid of scale insects is to peel them off individually with your fingernails, a knife, or tweezers, being careful not to damage the plant.
- You can also use a Q-tip dipped in rubbing alcohol to kill them.
- Check the base of the plant because scale can affect roots as well.
- You may need to remove heavily infested parts of the plant.
Spider Mites
These tiny arachnids can be white, brown, or red, but are almost invisible. You probably won’t know they’ve attacked your plants until you see fine dense webbing around the edges of the leaves and stems. Symptoms of spider mite damage include brown and yellow speckled leaf discoloration, or extreme cases, yellow or dying leaves. Spider mites thrive in dry conditions, so under watered plants are more susceptible. They can become even more of a problem in the winter when humidity levels drop indoors. Treatment:
- Clean leaves with soap and water, then polish them with neem oil.
- Raise humidity by keeping your plant in a bathroom, using a humidifier, or misting it with water.
- You can also spray the affected plant with a 1 part rubbing alcohol, 3 parts water mixture to kill the mites. Try it on one leaf first to make sure your plant isn't too sensitive.
Common whitefly
Image from Wikimedia
Whiteflies are usually less than ⅛ inch long, and resemble small white moths. They are easy to detect, because when disturbed, a cloud of them will fly away from an infested plant. Whiteflies usually cause minimal damage, but could cause unsightly discoloration or stunt your plant’s growth. They live on the undersides of leaves, so be sure to check there thoroughly for eggs. These indoor plant pests are more common in the late summer when humidity rises, but can come from greenhouses any time of year.Treatment:
- Take your plants outdoors and hose them off, then spray the undersides of the leaves with a dish soap and water solution.
- Wipe the undersides of the leaves with neem oil spray to discourage the whiteflies from returning.
- Try to do these treatments in the morning or evening, when whiteflies are less active.
