Dealing with Pests on Indoor Houseplants
A common problem with houseplants is an infestation of a plant pest. These can come from a newly purchased plant or a plant you enjoyed on your porch or deck for the summer.
How to Prevent Houseplant Pest Infestations
One of the most effective ways to avoid houseplant pest infestations is to take preventive measures. Whether you’re bringing home a new plant from the store or moving your beloved bougainvillea indoors for the winter, it’s important to isolate new or outdoor plants for at least a month before introducing them to your indoor collection. Pests can take two to three weeks to reveal themselves, so inspect your plants thoroughly during this time. Using an insecticidal soap and systemic insecticide when transitioning plants indoors can help prevent infestations. By closely monitoring and separating your plants for a few weeks, you’ll catch any potential problems before they spread to your entire collection.
How to Spot Pests on Your Houseplants
Pests can often hide in plain sight, causing damage to your houseplants before you even notice them. The key to maintaining healthy plants is catching these issues early. By paying attention to subtle changes in your plants’ appearance and growth, you can identify common pests and take action before an infestation worsens. Below are some telltale signs to watch for, along with tips on how to recognize and treat different types of houseplant pests. Keep reading to learn about effective solutions to keep your plants thriving!
Signs Your Houseplants Have Pests
Houseplants can show different symptoms based on the type of pest they’re affected by. To help you identify and address these issues, here are some general warning signs to watch for. Keep reading to learn more about common pests and effective treatments to keep your plants healthy.
- Failure to Thrive Despite Good Care – This can indicate that sap-sucking pests like aphids, mealybugs, or spider mites are stealing nutrients from the plant.
- Yellowing Leaves or Spots – This often points to pests like spider mites, thrips, or whiteflies. They typically damage plant cells by sucking out the sap, leading to discoloration.
- Visible Bugs on Soil or Plant – Some pests like fungus gnats (larvae in the soil) and scale insects are noticeable on close inspection. Even if you can’t see them easily, it’s wise to check with a magnifying glass.
- Flying Gnats or Flies – Fungus gnats often hover around the soil of overwatered plants, especially in humid conditions.
- White Cotton-like Substance – This is a classic sign of mealybugs, which hide in plant joints and excrete a white, waxy substance.
- Webbing or Cobwebs – Indicates the presence of spider mites, which create fine webbing as they feed on plant leaves.
Common Houseplant Pests and How to Treat Them
Spider Mites
A spider mite infestation will show up in yellowing leaves or yellow spots. The plant fails to thrive, and a bad infestation will have very fine webbing in between the leaves and stems. Spider mites can be seen with a magnifying glass, but a quick test is to take a sheet of white paper and position it under the leaves. Tap lightly. Are there moving black specks on the paper? You’ve got them. They can be treated with neem and/or insecticidal soap. When using an insecticide, always read the label and follow the directions, as well as testing a leaf or two first to make sure it doesn’t harm your plant.
Mealybugs
Mealybugs are white and cling to leaves, usually the new leaves or at the joints of leaf and stem. They look like little white or light brown bugs with “legs.” You may see a cottony white stuff on the joints of leaves. The “cotton” is a very good indicator of a mealybug infestation. The bugs themselves have a waxy coating which is fuzzy and the eggs are protected by the same fuzz. A good overview of mealybugs and treating them can be found here: https://hort.extension.wisc.edu/articles/mealybugs-2/
Scale
Scale is a variety of pest that will stay in one place on the stem as an adult. The larvae crawl to a good spot and then grows a somewhat hard shell. They are usually brown or black. A good indicator of a scale infestation is the sticky sap they exude. Keep in mind, some plants naturally exude a sticky sap – the flowers of a certain hoya variety comes to mind. Scale requires some diligence to treat, although you can simultaneously use an insecticidal soap or oil along with a systemic which is taken up by the plants. A very good Colorado reference is at the Colorado State Extension website: https://extension.colostate.edu/topic-areas/insects/brown-soft-scale-a-common-insect-pest-of-indoor-plants-5-599/
Whiteflies
Flying plant bugs are obvious from the start. Whitefly is a small white flying insect which is also a sucking insect. Whiteflies can be treated with neem oil and sticky traps, which can be purchased from your local nursery or hardware store. The traps attract the adults and the neem oil treats any eggs or larvae. Additionally, the plant can be treated with a systemic in conjunction with the insecticidal soap or oil. Whiteflies will colonize other plants very readily without being near them as they fly rather than crawl.
Soil Gnats
People often ask, “what is that little black gnat that seems to be flying around our heads?” It is a soil gnat. These gnats actually live in the soil and not on the plant. Many potting soils have not been sterilized properly, and as a result these gnats appear soon after repotting or in a newly purchased plant. Soil gnats love a moist environment. A sticky trap will help get rid of the adults but spraying the plant is not going to help. Soil gnats will stop reproducing once the soil dries out on the top 3 inches. If possible, water from the bottom of the plant or let it dry out between watering so the soil can’t sustain the gnat larvae. Not all commercial potting soils are alike. A better quality soil is more likely to have been treated properly for these pests. I recommend Happy Frog products to people for repotting. It has been a successful medium for most of my plants and I have not had a problem with the gnats.
Need Help Managing Houseplant Pests?
Bugged by bugs? Don’t worry—I’m here to help! With my expert houseplant consultation services, I can provide a thorough diagnosis and a personalized treatment plan to ensure your plants stay healthy and pest-free. Whether you’re struggling with spider mites, mealybugs, or any other pest, reach out today for professional advice and a solution tailored to your plants’ needs.
