Guide to Houseplants: How to Get Rid of Pests

When it comes to houseplants, there aren’t many beneficial insects. In fact, insects often cause more damage than benefits for houseplants.  So, what do you do when you find bugs on your houseplants?  Do you throw out the plant?  Can you save your houseplant from pests?

Luckily, at Head-Lee Nursery in Seneca, South Carolina, we have over 40 years of horticultural experience.  We know houseplants inside and out, so we know how to get rid of pests on houseplants.

Here are some of the most common insects that can infest and harm houseplants and how you can get rid of them.

Gnats

Not only are gnats annoying, but they can damage plant roots too.

Usually, fungus gnats are attracted to plants that have been overwatered. The fungus gnat larvae bury themselves in the wet soil and damage the plant’s roots as they feed.

How to Get Rid of Gnats

Actions to Take

First, isolate your plant so that the gnats don’t spread to your other plants. Then, dry out your plant as much as it will tolerate.

Repot your plant into a container with ample drainage. If you don’t have another pot, then clean your current container with soap and water and make additional drainage holes if necessary. Use new soil to repot your plant.

As you finish your plant’s cleaning, ensure there are no areas of standing water in your home. Gnats love standing water, and eliminating those areas will reduce the odds that the pesky critters will return.

Mosquito Bits

Use products designed to kill any gnat larvae left behind. Mosquito Bits, which are pet-friendly, can be sprinkled on top of your soil or used as a soil additive.  

Diatomaceous Earth

Use diatomaceous earth on top of the soil. Diatomaceous earth is crushed up siliceous diatom fossils and is very powdery. It sucks up moisture and strips away fungus gnats’ natural waxy coating as they move through the powder. Essentially, diatomaceous earth dehydrates gnats.

Diatomaceous earth is pet-friendly, can be effective for killing ticks, and can be used both inside and outside. It can be a soil additive or sprinkled on top of your plant’s soil. However, diatomaceous earth can be messy, so have your vacuum cleaner on hand.

Sticky Traps

You can also control gnats with sticky traps, which will catch the flying adults. Insects are attracted to vibrant colors, so use traps that are bright colors, such as yellow.

Scales

Scales are small, flat, and oval-shaped. They are usually brown or tan and have a shell on them that looks like a small scale. 

These insects target leaves’ undersides and joints (where the leaves join the main stem) and infest a plant through contaminated soil. This can happen through a contaminated pot or when a plant has been left outside and then brought inside. Unfortunately, scales are tricky little buggers who are impervious to most pesticides.

Scales create sticky residue (known as “honeydew”) on plants, which leaves the plant susceptible to sooty mold and damages the plant’s immune system.  Also, scales suck the lifeblood (sap) out of a plant, which can weaken the plant, cause poor growth, and result in leaves yellowing, becoming deformed, or falling off. Scales can also create brown pock marks on the plant. Without intervention, scales will kill your plant.

How to Get Rid of Scales

Actions to Take

Isolate your plant for at least three weeks.  Then, thoroughly search your plant for scales using a magnifying glass. They will usually be under leaves and on stems. Remove the infected areas and put the trimmings in the trash. Do not compost them.

For any remaining insects, pour rubbing alcohol into a small container, dip a cotton swab into the rubbing alcohol, and put the soaked swab onto each scale. You may have to scrape away any remaining insects if they refuse to fall off.

Wash off your plant in the sink if possible. Then, wipe away any remaining scales with a damp, microfiber cloth.

Change out the dirt and sanitize the container before using it again.

Insecticidal Soap and Neem Oil

To deal with any remaining scales and their larvae (which are not easily visible), spray neem oil on all of your plant. You can also use an insecticidal soap. However, some brands can damage houseplants, so always do a test leaf first to see how your plant reacts before you spray the whole plant.

Mealybugs

Mealybugs are related to scales and, like scales, they are oval-shaped lifesuckers. They secrete a protective coating that looks like powdery, white wax or cotton.

Mealybugs encourage sooty mold to grow on houseplants, and they cause yellowing leaves. They can also encourage ants to invade a plant since mealybugs cause a plant to secrete its sweet sap (an ant’s favorite snack).

How to Get Rid of Mealybugs

Actions to Take

Isolate your plant and then scrape away any white spots or residue. If your houseplant isn’t fragile, then blast off the mealybugs with water.

An alternative treatment is to dip a cotton ball or gauze into isopropyl alcohol (70% alcohol) and wipe away the mealybugs. Do a leaf test first to ensure that your plant doesn’t react poorly to the alcohol. Repeat this process each week until you no longer see any mealybugs.

Insecticidal Soap and Neem Oil

Spray your plant with insecticidal soap (a homemade version is one teaspoon of dish soap mixed with one gallon of water) or a neem oil mixture (two teaspoons of neem oil, two teaspoons of dish soap, and one gallon of warm water). Do this weekly until the mealybugs disappear.

If the infestation is getting out of control, then consider using a synthetic pesticide.

Spider Mites

Spider mites are prevalent pests in South Carolina gardens, and they can infect South Carolina houseplants.  These tiny arachnids are green, gray, brown, orange-red, or yellow. They move rapidly like crabs over a plant when they are disturbed.

Spider mites suck out the plant’s sap, thereby decreasing the plant’s nutrients. They also disrupt the plant’s chlorophyll production.

Some tell-tale signs of spider mites are 1) webbing on your plant, 2) small holes in the plant’s leaves, 3) small white or yellow spots on the leaves, 4) new plant growth that fails to flower or unfurl or looks misshapen, or 5) yellowing or dropping leaves.

If you think you may have spider mites but aren’t sure, then wipe a leaf on a piece of white paper. If you see small, moving dots, then you probably have spider mites.

How to Get Rid of Spider Mites

Actions to Take

Isolate your plant and then blast the spider mites off of your plant with water. Wear gloves and long sleeves as spider mites can bite humans, and the bites may cause itching, swelling, or a rash.

Neem Oil

Apply neem oil to your plant since the oil clings to the spider mites and kills them.  The problem is that you need to touch the spider mite with the oil for this to work.  You can also try a miticide or pyrethrum, which is a botanical insecticide.

Consult Head-Lee Nursery for Houseplant Help

At Head-Lee Nursery in Seneca, we know how to get rid of plant pests and how to rehabilitate houseplants after an infestation.  Stop by our South Carolina garden center or give us a call at (864) 882-3663 for advice on how to get rid of pests on houseplants.  

While you’re here, check out our wide selection of healthy houseplants, gardening supplies, and pest control options.  We have diatomaceous earth available at our South Carolina garden center as well as neem oil, Mosquito Bits, and other products.