Conquering Houseplant Pests

We’ve all had our pest struggles. You know . . . the day you return home from a long-weekend getaway to find white mealy bugs on your newest houseplant plus two others beside it. Relax, pests don’t have to be a death sentence for your plants. We’ve put together a crash course to help you cope with the most common ones.

Inspect New Plants

Most pests arrive on new plants, so a careful inspection is a must before purchasing them at a store or farmer’s market. For online orders or plant gifts from friends, be sure to inspect new arrivals carefully before placing them with other houseplants. Remember to check under leaves and around the base, too. We even recommend a two-week quarantine for new plants, since invisible pest eggs or younger pests may be hard to spot.

Avoid Stressing Plants

One of the best defensive strategies is to keep your houseplants in peak shape. Prevent stresses like overwatering, underwatering and cool drafts. Your healthy plants will thank you and be better equipped to fend off pests.

Protect the Good Guys

Before we dis on the bad guys, we want to let you know there are plenty of good guys or “beneficial insects” that we don’t want to harm. We’re especially talking about summertime when we’re growing houseplants outdoors. Here, it’s important to allow predatory bugs like lacewings, spiders, ground beetles and ladybugs help out by devouring harmful pests on your plants. We remind our customers to embrace these beneficial bugs and let them do their jobs. After all, plants are amazing living organisms and not statues. 😉

“When we kill off the natural enemies of a pest, we inherit their work.” – entomologist C.B Huffaker

Learn to ID and Treat Pests

Each time you water your houseplants, take time to inspect them for pests. If you spot something, take a closer look using your phone’s flashlight or even borrow a magnifying lens from your kiddo’s science kit. Early infestations can be easily treated. Just separate the infested plants from your healthy ones until all the pests are gone. Here are a few tips for identifying and treating several common pests.

• Scale: These sucking insects appear as clusters of raised bumps or scabs on leaves and stems. They vary in color from brown to orange to white and may leave a sticky residue as they feed. For small infestations, simply take them to the sink and scrape or wash them off. Also, try wiping them with cotton swabs dipped in rubbing alcohol. For more serious infestations, spray the plant with multiple applications of an insecticidal soap – either store-bought or homemade (one teaspoon of mild dish soap like Ivory or Dr. Bronner’s and one gallon of water). You can also suffocate them by spraying with horticultural oil, either in a pre-mix solution or your own made from neem oil concentrate. Always follow package instructions, and be persistent with applications since scale can be pretty relentless. For succulents, avoid applying any oil-based products which can ruin their waxy coating; instead, go with an insecticidal soap.
• Mealy bugs: These other plant suckers look like fuzzy white cotton or snow around stems and leaf nodes. They’re related to scale and can be treated in the same way as detailed above. Alcohol swabs work the best; just be diligent to continue treating until all mealy bugs are gone.
• Aphids: These little guys are usually found on the undersides of leaves in clusters or colonies of pin-headed sized specs often translucent green-pink or red. First try blasting the aphids with water from an outdoor garden hose or indoor kitchen faucet sprayer. Treat remaining ones with horticultural oil or insecticidal soap. Another option is hot pepper wax, a natural repellent made of capsaicin that discourages aphids as well as white flies and spider mites.

• Thrips: Thrips are tiny straw-colored insects with feathery wings. They’re very easy to miss with the naked eye, so try moving a leaf to spot their line of movement especially around leaf veins. Patchy discolorations are another clue of thrips’ damage. To treat thrips, first try dislodging as many as possible with a faucet sprayer or outdoor garden hose. Next, treat with Spinosad, a natural substance found in products like Captain Jack’s Deadbug Brew. Be sure to follow package instructions.
• White Flies: These tiny, white moth-like flies are found on the undersides of leaves. If you touch the plant, they’ll quickly take flight. They multiply fast and suck the sap from plants leaving them wilted and yellowing. Try trapping them with yellow sticky cards placed above the plants or spray applications of horticultural oil.
• Spider Mites: A fine silky webbing is a sure sign of spider mites. Look closer, and you’ll see teeny-tiny specks crawling around the webbing. First, take the plant outdoors and spray it with a garden hose. If it’s winter, try blasting at the kitchen sink with the faucet sprayer. Be sure not to miss the undersides. Let the plant dry, then apply a horticultural oil to smother any lingering ones. Reapply the oil two more times every 10-14 days.

Smart Pest Control Strategies

At Groovy Plants Ranch, we always encourage customers to first try to physically remove insects then treat remaining ones. Some hacks for physically removing them include a sticky lint roller, a wet cloth or a blast of water from a garden hose, hand-held shower head or sink faucet sprayer. Next, when treating remaining pests with spray products, always follow the package directions and try placing houseplants in a shower to contain overspray from treatments.

Moving Plants Indoors and Out

Before moving plants indoors in the fall, blast off any hitch hikers with a spray of water from your garden hose, then check for any linger ones.

In summer, return houseplants outdoors. Here, natural predators, like ladybugs and parasitic wasps, will do more work than you can. Plus, the elements will help toughen your plants and make them less hospitable for pests.

Knowing When to Say Goodbye

Sometimes, it’s best to toss your infested houseplants and buy new ones. While that advice may sound a bit self-serving from a plant store, we encourage you to weigh your time and treatment costs versus the costs of new plants. It’s your choice – no judgment here. Sadly, we all lose plants but are grateful for the wisdom gained along the way.

For more info, check out this detailed guide by Summer Rayne Oakes, an entomologist (aka, “bug scientist”) and author of How to Make a Plant Love You. Also, here’s an extensive product guide by Clemson University’s Cooperative Extension.