How to Handle Indoor Plant Pests

Last month we went over indoor plant care, and part of that is identifying and controlling pests that indoor plants can be prone to. Sometimes it can feel like no matter how well you take care of a plant, you still end up with fungus gnats, or your plant leaves yellowing and drooping. In this month's blog, we will go over how to identify the most common pest problems, and how to treat them, and it won’t have to end in rehoming a plant!

Types of Pests

There is a wide range of pests that can infect your indoor plants, posing a threat to the plant's health and the health of other plants in your home. If one plant is affected, you want to make sure to address it right away, before it has a chance to spread to the other plants in your home, or before it harms the plant. The most common pests are:

• Scale bug

• Mealybug

• Fungus gnats

• Spider mites

Fungus Gnats

Fungus gnats are those annoying fruit fly-like pests that hover around your houseplants. They are attracted to damp soil and adult gnats will lay their eggs just below the surface. Once hatched, the larvae will burrow into the soil and feed on fungi and decaying plant matter. If the infestation is big, the larvae can feed on the plant’s roots. If this happens, your plant will look similar to that of root issues or root rot, where the bottom leaves will turn yellow, fall off, or the plant becomes stunted. They look similar to a mosquito, but smaller, about ⅛  inch in size, and are not strong fliers, so they tend to walk along the soil surface. To get rid of them, you can either use yellow sticky card traps that have a sticky adhesive to trap the gnat, and they are attracted to the yellow color. They can be placed on the soil surface, or stuck to a skewer. Apple cider vinegar is another good method where you add equal amounts of apple cider vinegar and water, then add a few drops of dish soap to a shallow dish. The liquid should be at least ¼” deep. Place near the base of the plant or set directly onto the if there is room in the pot, refresh every few days.

Spider Mites

Spider mites can be most commonly found in warm, dry environments with low humidity and can look like a tiny reddish-brown spider only 1/50 of an inch long. They feed on the sap of the plant, so can be spotted by the plant's leaves turning stippled, yellow, and weak. They can be hard to spot, so also look for finely spun webs. To combat an infestation, move the plant away from other healthy plants, and put it in a cool room if possible. The foliage can be cleaned with a soft washcloth or a forceful spray of lukewarm water. Another option is to use rubbing alcohol diluted with water, typically a 1:1 ratio, or 1:3 of more parts water for sensitive plants. This will not harm the plant, but a small test patch can be done just to be sure before doing the whole plant. Use a spray bottle to spray the mixture all over the plant, and either let fully evaporate or use a soft cloth to wipe the foliage.

Scale Bug

Like spider mites, scale bugs also like a warm, dry environment, and are small and oval in shape. They tend to be flat with a tan to brown shell-like covering like a scale. They feed on the sap of a plant and can be mostly found at the joints of the stems, or on the underside of the leaves. Signs your plants may have an infestation are similar to the other pests, where the plant's leaves will turn yellow and drop, and the plant will look sickly. To combat the infestation, isolate the plant from your other houseplants to avoid it spreading. Use a cotton swap dipped in rubbing alcohol and apply it directly to the scale bug. You may need to pry the bug off as well. Try and get as many of the bugs with the alcohol swab, making sure to check all joints and under all leaves. Also, check the soil near the base of the plant to see if any bugs are hiding there. Use a soap and water mixture and spray on the plant to help wash off any remaining bugs. Replacing the top layer of soil and pruning any heavily infested leaves will help remove the bugs, but you may need to do a few treatments before the bugs are gone.

Mealybug

Mealybugs are small oval white bugs that are covered in wax and are like scale bugs without the protective shell. They also feed on the sap of a houseplant. An infestation can look like your plant is covered in a white cottony substance, and can look like a fungus or mildew. Removing a mealybug infestation is a lot like the scale bug, and a cotton swap dipped in alcohol applied directly to the bug will kill it. You may also be able to use a steady stream of water. This treatment can be used for light infestations and some plants may not like this version. It will most likely take multiple treatments, so make sure to check daily and check over the plant really well, including the soil.

For many of the most common pests, treatments are very similar in how to remove an infestation. One of the most important steps is to isolate the infected plant and not re-introduce it to being around other houseplants until the infestation has been completely dealt with. Check other plants for any signs the pests have spread and make it a habit to frequently check plants for the best chance at catching an infestation before getting too big. If one has gone too long, tossing the plant may be your only option. Regular maintenance and overall plant health are key to avoiding this.