How to Identify and Control These Common Houseplant Pests

Our house plants become established members of our home, filling our rooms with life and greenery. They clean our air, boost our moods, and act as living decor. While plants are welcome housemates, they can unfortunately be accompanied by unwanted guests. Houseplant pests can make our indoor jungle become a desolate landscape. Even the most well cared for plants can harbor pests. They come in many forms, are treated in different ways, but all can cause severe harm to our plants.

Being able to identify the pest is key for creating a plan of action to save the infested plant, and prevent the pest from spreading to even more houseplants. To keep our houseplants pest free, here are some key identifiers and symptoms of common pests, and how to treat them.

Common Whiteflies

White flies are commonly mistaken for small moths, because of their appearance and habit of flying about if they are disturbed. A common sign of white flies are prematurely yellowing leaves, because the pest feeds off the plants moisture, literally sucking the life out of it. Both adults and their nymphs are unwanted on any plant, and are destructive in both phases of life. Adults lay their eggs on the plant, and a week later the nymph will emerge. They crawl to find their own part of the plant, and use their mouth to suck nutrients from the plant. This process continues as nymphs turn into adults and adults lay more eggs. If left untreated, the waste they excrete from eating the plant can attract harmful molds.

Swarms of whitefiles on a leaf

Treatment: Yellow sticky traps can help with adults, but nymphs will need to be washed off using high pressure water and a dish soap solution. Mix five tablespoons dish soap with one gallon water, mix and spray onto the plant. Neem oil or insecticidal soaps can also be sprayed onto the plant if the infestation is still progressing.

Mealy Bugs

Mealy bugs are scale insects that can travel from one plant to another by using touching leaves as a highway. They have a soft white appearance, almost as if they are covered in cotton. Their eggs (which can be laid at a rate of 600 per female) also have a cottony web like appearance. After ten days the eggs will hatch, and the nymphs will spend the next four to eight weeks using the plant as food. They suck the juices out of their host plant, specifically targeting new growth. Leaves will begin to yellow and fall off.

Mealybugs suck sap from the leaves and stems of plants

Treatment: If you find mealy bugs, immediately isolate the plant. It may take several sessions, but washing away the bugs is a proven tactic. Spray the plants vigorously with water, and use an insecticidal soap or dish soap solution to wash the mealy bugs away. A five tablespoons to one gallon of water works well for a homemade soap solution. Neem oil can also be sprayed directly onto the affected areas. Keep plant isolated until the pests have been completely eradicated.

Fungus Gnats

Fungus gnats are more of an annoyance to humans than they are to plants. These pesky pint sized gnats have a strong resemblance to fruit flies, and are commonly seen buzzing above soil, especially after recent waterings. Adults lay their eggs directly into the soil. Their larvae love moisture, and feed off of the fungi found in soil. Thankfully the soil normally provides them with enough nutrients to leave the plant itself alone, but their ability to multiply and fly around our home makes them an unwelcome pest.

Fungus gnats look a lot like fruit flies floating around the plant

Treatment: Treatment for fungus gnats is fairly easy, by using bacillus thuringiensis (commonly referred to as BTI). It is a safe bacteria that can be scattered on the soil and stops the infestation at its source. Yellow sticky traps can be used to catch the remaining adults.

Spider Mites

Spider mites are incredibly hard to see, but their damage to the plant is not. Reddish brown spots will appear on your plant, evidence of this harmful pest. The spider mites themselves are normally a reddish brown or cream color, living in large colonies that prefer to feed on the undersides of leaves. These leaves will eventually lose all nutrients, yellow, curl and fall off the plant. Another sign of a spider mite infestation is webbing underneath leaves and at the bases of stems.

Houseplant under attack from spider mites

Treatment: Spider mites are notorious for being difficult to get rid of. Isolate the plant and trim away the affected areas. Spraying the plant with high water pressure can greatly reduce the pest population, especially when done often. Insecticidal soaps and neem oil can also be sprayed on to help eliminate remaining pests. If this does not work, a stronger insecticide may have to be incorporated.

Common Brown Scale

Common brown scale bugs are unique insects, and almost doesn't look like an insect at all. They appear as small bumps that seem to be a part of the plant. They are only mobile for a short time after birth, and will disperse to find a portion of the plant to attach themselves to for the next sixty-five days, sucking nutrients from the plant. Their outer shell acts as a cap that protects them once they are attached to a plant, making it difficult to get rid of them. They can spread to additional plants if any leaves are touching.

Common brown scale infestation on a plant

Treatment: Treating scale insects can be challenging, and in some cases it may be best to throw the whole plant away before the pests can infest any other plants in your home. If this is not an option, then there are a few options, but timing is of the essence. During the mobile larvae stage, neem oil can be sprayed on the insects. However, if the scale bugs have attached themselves to the plant and have their protective cap, there are fewer options. Stronger insecticides can be used, or if the infestation is mild, a cotton swab dipped in rubbing alcohol can be dabbed directly onto the insects. Plants can be trimmed, taking away stems and branches that have been affected.

Aphids

Even though they are known to be a common outdoor pests, aphids can invade our indoor spaces as well. They come in a range of colors, and can be white, black, brown, gray, yellow, light green, or pink. They feed off of our plants by sucking the nutrients from leaves and stems. They tend to stay in groups and most varieties are flightless. However it is possible for winged aphids to appear, making it harder to control a population to just one plant. Their waste is a sticky substance called honeydew that can attract additional pests and sooty molds. Plants with aphids will have yellowing curled leaves that will fall when enough nutrients are taken by the aphids.

Aphid infestation on a plant

Treatment: Thankfully these unwanted pests are relatively easy to control. Cool blasts of water can be enough to dislodge the aphids and take care of the problem. A light dusting of flour can also be placed on the plant to disrupt the aphids digestive system. Neem oil, insecticidal sprays and diluted dish soap can also be used to clear out the pests.

Pest Prevention

The key way to make sure you don’t have unwelcome pests on your plants is prevention. Here are the key ways to prevent pests from ruining your indoor jungle:

  • Look before you buy. While shopping for new plants, make sure to look under leaves, on stems and in the soil for any signs of pests. Big box stores are more commonly affected by pests, so take special care to look through the foliage before bringing the plant home.
  • Social distance. When bringing a new plant home, it is a good idea to quarantine it from other plants in case the pest does not show up at the store. For the next few days, keep the plant by itself and check the plant for any sign of infestation. If the plant shows no signs of pests, it is ready to go in its desired spot. Along with the quarantine, make sure its leaves aren't touching any other plants for a few days. Many pests need a “bridge” to transfer from one plant to another, making touching leaves a highway for them to travel on.
  • Use clean soil. When repotting a plant, it is always a good idea to use new fresh soil. Old soil that has been left out can harbor eggs from previous pests.
  • Consistent watering. Pests, like fungus gnats, thrive off of constantly moist environments, so be sure to let the soil dry out between waterings to prevent the perfect pest habitat from forming.
  • Healthy plants. A healthy plant is more likely to survive and even detour a pest from invading. Keeping plants vibrant and strong can help in your battle against pests.