Common houseplant pests are something to be aware of. No matter if you only have a few leafy friends adorning your interior or a sprawling collection, these pesky insects can show up when you least expect them. And, unfortunately, they can cause various problems, such as weakened growth and leaf discolouration.
While pest control is one of the more frustrating aspects of caring for indoor plants, rest assured that most interlopers can be easily dealt with, especially if you catch them early. Repeat treatments are usually necessary, but the sense of reward when your once-affected plant bounces back to full health makes the effort well worth it.
I asked multiple plant-care experts for their insights into common houseplant pests, including tips on identifying and tackling them. Whether you're dealing with thrips or fungus gnats, this advice will help.
5 common houseplant pests and how to get rid of each
Looking after your best indoor plants properly is the first step in keeping them pest-free. As Kelly Dyer, plant doctor at Patch Plants, explains, houseplants are more vulnerable to pests when they are stressed or their health (immune system) is compromised.
"Healthy plants, like healthy bodies, are more resilient and able to fight off pest infestations," she says. "The best approach to pest management is to ensure healthy plants by placing your plants in the light and environmental conditions they prefer (this varies according from plant to plant so do a bit of research), by watering them according to their needs, by feeding them throughout the growing season, and repotting them every two to three years to ensure healthy root growth."
How to identify and get rid of fungus gnats
I've dealt with my fair share of fungus gnats, also known as sciarid flies, when caring for spider plants. Despite being tiny, they are definitely annoying as they hover around the house in swarms.
My mistake, I realised, was using pots without drainage holes at the bottom, as damp soil attracts these insects. It's also important to know how often to water houseplants, as overwatering can help keep them at bay.
Kelly notes that the adult flies lay eggs in the soil surface and their larvae feed on rotting organic matter. "They’re not really harmful to the plants, but may eat roots that soften in moist soil," she says. "They’re more prevalent over winter when soil is sitting wet for longer, as plants aren’t drawing up as much water to use in the processes of photosynthesis and respiration."
As well as letting the soil dry out between waterings, you can also try adding a layer of sand or decorative gravel on top of the soil to help deter egg-laying – a tip from Jo Lambell, founder of Beards & Daisies. "Sticky yellow traps can reduce adult populations, and a biological control like Bacillus thuringiensis israelensis (BTI) can target larvae," she adds.
You could also try using nematodes. These are microscopic insects that you can mix with water and apply to the soil, Kelly explains. "They feed on the larvae of sciarid flies specifically, interrupting the life cycle."
Alternatively, you can try repotting the plant into fresh soil, as suggests pest control expert Sophie Thorogood. "With this option, all the soil must be removed and some of the root structure to remove all the flies, larvae and eggs, which can be very small."
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How to identify and get rid of spider mites
"Spider mites are tiny, but the webbing they leave behind is usually a giveaway," says Jo. "They thrive in dry, warm rooms and will leave leaves speckled, pale, and eventually dropping off."
Her advice for tackling them includes increasing the humidity around your plants. There are a few ways to do this, from misting them regularly with a spray bottle (this metal plant mister from Crocus is suitably chic) to putting your houseplants in the kitchen or bathroom, which tend to be more humid rooms.
Jo also suggests wiping plant leaves with a damp cloth and spraying them with an insecticidal soap or neem oil. "Severe infestations may require repeated treatments," she adds.
RRP: £18.97 | A ready-to-use spray that tackles a wide range of pests, including spider mites, aphids, and thrips. As with any commercial spray, be sure to follow application instructions.
How to identify and get rid of mealybugs
"Mealybugs look like little fluffy white clumps on your plants, often hiding in the nooks and crannies," says Jo. "They suck sap and can quickly weaken a plant if left untreated." They also excrete a sticky substance called "honeydew", Kelly adds – this can lead to the growth of black sooty mould, which prevents plants from absorbing light.
Other signs of mealybugs include yellowing and mottling of leaves, and deformed leaves and buds (particularly of soft new growth), according to Kelly. She recommends regularly treating your plant with a soapy solution or a chemical-free bug spray as a preventative, as well as ensuring there is good air circulation.
"If you do find mealybugs on your plant, use a damp cloth to wipe them off, or a cotton bud or paintbrush dipped in pure isopropyl alcohol to physically remove any adults," Kelly says. "You can also rinse them off under room-temperature running water, making sure to get into the crevices. Repeat this regularly."
How to identify and get rid of aphids
Aphids can be a pain when growing garden roses, and sometimes they appear on indoor plants, too. "These are usually found clustering on new growth, often green but sometimes black or brown," says Jo. As sap-sucking insects, they can weaken plants and stunt growth. Like mealybugs, they also excrete a sticky substance, which can lead to black sooty mould.
To get rid of them, Jo suggests washing them off with a gentle stream of water, wiping down the foliage, or using neem oil or insecticidal soap. "Natural predators like ladybirds outdoors won’t be present indoors, so persistence is key," she adds.
Angharad James of Baby Bio® alternatively recommends using the Baby Bio® Houseplant Bug Killer Ultra Ready To Use (available from Amazon) for fast and effective control. She notes how it works in as little as one hour to stop pests feeding, with visible results in just a day and protection lasting up to eight weeks.
How to identify and get rid of thrips
Whether you're looking after a large monstera or a small pothos, thrips are another pest to be aware of. "Thrips are minute sap-sucking insects with narrow bodies (2mm)," says Kelly. "The adults lay eggs in plant tissue – usually the undersides of leaves – and once they hatch, the larvae feed on the green fleshy parts of the plant." She says they thrive in hot, dry air and are most prevalent from late spring to early autumn, although heated indoor environments over winter can prolong this.
"Because they're so small, you usually only notice them when symptoms start to appear – usually yellowing, mottled or silvery-white discolouration on the upper surfaces of leaves where the sap has been removed and the plant tissue starts to die," Kelly continues.
She says that encouraging humidity around your plants can prevent them, and you can also regularly spray your plants with bug control spray or a soapy water solution and let it dry on the leaves. "Rinsing or washing down the leaves under room-temperature water can also help dislodge pests. Use sticky traps to catch adult flies."
Another approach she suggests is to remove any thrips visible to the naked eye using sticky tape. "Repeat this in between spraying with a natural insecticide," she advises.
FAQs
When is a good time to check for houseplant pests?
"Most pests are more active in spring and summer, when the warmer temperatures encourage faster plant growth (and faster pest reproduction, too)," says Jo. However, keep looking out for them as part of your winter houseplant care. Jo highlights that central heating can create a dry environment that spider mites love, so it’s worth checking plants all year round.
It's also important to be vigilant when bringing plants into your home. As Kelly advises, "always inspect any new additions to your collection thoroughly".
What shouldn't you do if you spot houseplant pests?
"Don’t ignore the problem," says Jo. "Even a small infestation can quickly spread to other plants."
With this in mind, it's always worth isolating a plant while you treat it if you spot pests; however, putting it back in its usual place too early can also be a houseplant mistake. As Jo advises, you should only return it to your collection once you’re confident the pests are gone.
Looking for more tips and advice on keeping your indoor plants thriving? These common houseplant myths are worth bearing in mind, and our guide on looking after houseplants in a heatwave will also come in useful.
