Beat the Bugs: How to Overcome Common Houseplant Pests

“Get houseplants,” they said. “It will be glamorous,” they said. What’s the part they left out? The pesky pests. Between the spider mite infestation you have going and the fungus gnats that whirl around your TV at night, houseplant pests may be driving you crazy. What are some of the most common insects, and how can you beat them?

Fungus Gnats: The Most Annoying Houseplant Pest

The “fruit flies” that buzz around every plant parent’s house are called Fungus Gnats. These airborne bugs are aptly named because they feed on the fungus that is found in moist soil. The good news? While annoying, adult fungus gnats are harmless to your plants. 

It’s the youngsters that pose a small threat because they live within your plant’s potting soil. As a larva, these bugs feed on fungus, organic debris, and feeder roots (tiny, delicate, white roots your plant uses to soak up nutrients). In general, the larvae are satisfied with their fungus-forward diet, and if they have a sufficient supply, they won’t pose much threat to the roots of a healthy plant.

The Solution

1. Purchase and place yellow sticky traps in your home.
2. Allow your plants to dry out more thoroughly before their next watering. No moisture, no fungus, no food, no larvae!

Brown Scale: The Sedentary Killers

These sneaky houseplant pests come in disguise and are often disregarded because they do not look like insects. These bugs are usually brown-colored and look like a plastic dewdrop on your plant’s leaves and stems—their shiny appearance results from their waxy, scaly armor, which protects them from many common pest-treatments. 

These bugs pose a danger because they suck the sap from your plant’s leaves, stunting their growth and making your plant weak.

As adults, Scale bugs do not move; they cement in place. Interestingly, these insects give ‘birth’ to live offspring instead of laying eggs. Why is that noteworthy? Immature Scales are mobile and travel to find their perfect “forever home” (usually on some new growth). To contain a Scales infestation, you must ensure that none of your plants physically touch the infested plant. 

The Solution

As noted, the adult Scale’s unique armor makes it impenetrable to standard pesticides. Focusing on killing the softer, mobile youths is not a real solution either, as the parent-bugs will simply keep producing more. It should be noted; Scales are challenging to get rid of. Follow these steps for your plant’s best chance:

1. Cover your plant’s soil with plastic or a towel.
2. Thoroughly spray the foliage with insecticidal soap.
3. Rub off each Scale you find with your fingernail or a firm toothbrush. Make sure to investigate every part of the plant to ensure there aren’t any hiding.
4. Use a heavy stream of water to spray your plant down, removing all the soap.

You must continue checking your plant for more Scales. If you notice one or two (and do not have time to repeat the above steps), dab them with a cotton swab soaked in rubbing alcohol, wait a few minutes, and then wipe them away with a soft cloth or your fingernail. 

Spider Mites: The Tiny Terrors

These houseplant pests are practically invisible to the naked human eye. How can you tell if your plant is struggling with them? Your leaves will appear discolored because Spider Mites feed on your plant’s pigment. They live on the underside of leaves and plant stems.

The tell-tale sign of Spider Mites? Delicate webbing with little white, red, or dark suspended polka dots (actually bugs). If you have a severe infestation, whole leaves will start to turn yellow, your plant’s health will decline, and leaves will start dropping one-by-one.

These pests are highly spreadable, so you must fully quarantine the affected plant.

The Solution

1. Spray down the foliage of your plant.
2. Wipe the fronts and backs of leaves thoroughly with a soft cloth.
3. Place it (in quarantine) near a humidifier.

Spider mites thrive in dry conditions. Maintaining humidity after treatment is essential. If your Spider mites are persistent, repeat the process and use insecticidal soap.

Leaves that Spider Mites damaged will not repair themselves. While they pose no further threat to your plants, you can remove these leaves with clean shears if they ruin your jungle aesthetic. As always, research your specific plant variety to find the best method.

Thrips: The Squirming Scoundrels

While this is a ‘less common’ houseplant pest, it still gets an honorable mention. These insects are small but visible, appearing long and slender. They puncture the outside layer of your plant’s leaf, feeding on its nutrients and leaving silvery streaks or specks. Thrips also affect new growth, causing it to become twisted and deformed.

Thrips are contagious, so quarantine your affected plant. 

The Solution

1. Spray your plant thoroughly with a contact insecticide, like Neem. (Cover every inch of leaf, front and back!)
2. Wipe your plant with a soft cloth.
3. Place blue sticky traps in your plant’s pot. (Thrips are attracted to blue, so don’t repurpose gnat traps.)

Mealybugs: The Fuzzy Fiend

These insects are related to the Brown Scale but are unarmored. Another pro: They look like white poof-balls, so they’re easily detected. Defeating Mealybugs might sound like a piece of cake, right? Think again: Mealybugs are mobile. This makes them highly spreadable and allows them to hide when under attack. 

Mealybugs are prolific reproducers. One mother-bug can lay 600 eggs at a time on the backside of leaves or stems. So, if you only miss one bug during your pest treatment, you could have 601 by tomorrow. These unwelcome guests can get out-of-hand quickly!

The Solution

• If you have caught the infestation early on, dab each mealybug with a cotton swab soaked in rubbing alcohol. 
• If you are highly adventurous (or desperate), you can release beneficial insects in your plant’s environment, like the “Mealybug Destroyer.” (Yes, that’s their real name.)
• If your infestation is severe, it is recommended that you get rid of your plant. While this seems drastic (and can be expensive if you have a rare beauty!), these houseplant pests pose an astronomical threat to your other plants. 

How to Prevent Houseplant Pests

Let’s state the obvious: There is no way to absolutely avoid all insects when you own a houseplant. Some kind of infestation happens to every plant parent, one time or another. However, there are specific steps you can take to minimize the risk of bringing these insipid insects inside.

Closely Inspect Your Plants

When purchasing a new plant, whether in a brick-and-mortar store or online, thoroughly inspect your plant before bringing it into your home. 

• Look for physical signs of pest damage: discoloration, distorted growth, any brown sticky residue. 
• Check the front and back of leaves for insects.

Quarantine New Plants

The offspring of many pests live in the soil and emerge when they are fully mature. Generally speaking, it is not recommended to immediately repot your plant after purchase, so that means you must quarantine it. Isolate your new houseplant for up to two weeks to allow any hiding pests to reveal themselves before introducing them to your other plants.

Use Fresh Soil

If you’re tempted to use an old potting mix from last season, don’t do it. There could be a plethora of eggs just ready to hatch. Remember, insect eggs “overwinter,” meaning that they can still hatch the next spring.

Maintain Your Plant’s Health

Weak houseplants are more susceptible to pest invasions. So, give your plants their best chance by researching the care regime they need and sticking to it. As already noted, high humidity wards off some insects and is usually required for healthy tropical plants.

Clean Your Plants Regularly

While this might not prevent pests from coming in the front door, it can reduce the risk of outright invasion. Inspect your plant’s leaves each time you water, and take the time to wipe them (front and back) with a damp, soft cloth. 

Keep Away from Cracks

We all love putting plants in window sills, but it comes with a risk. Poorly sealed windows create an open door for tiny insects to enter your home. By adding a “delicious temptation” to your windowsill, pests will undoubtedly come. Ensure all cracks are sealed before placing your plant near an opening, using caulk to fill any holes.

Know When to Give Up

No one likes to admit defeat, especially when our favorite plant is involved. But, the truth is: it isn’t a fair fight. 

Pests target unhealthy houseplants, making their health decline even further. Many insecticidal soaps (and chemical insecticides) stress out your plant. So, even if you succeed in eliminating all of the harmful insects, you end up with a weak, damaged plant that’s just inviting more pests. Will it have the energy to survive? Hopefully! 

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Prevention is ideal. Keeping a vigilant eye and catching pests as soon as they appear is your best bet. Are you defeating an entire colony of pests? We wish you success in your bug-beating ventures!