No matter what the season, filling your indoor space with houseplants is a great way to bring nature inside and get your garden therapy in the warmth and comfort of your home. Having plants in the house feels both refreshing and cozy, until…yuck! Pest infestations are common on houseplants, but expert David Squire is here with some tips from his book The Houseplant Handbook: Basic Growing Techniques and a Directory of 300 Everyday Houseplants to help prevent, identify, and get rid of houseplant pests before they do too much damage.
By David Squire
Few plants can completely escape from pests and diseases or cultural problems. It is much easier to prevent attack by pests and diseases than to eliminate them from badly affected plants. Here are some prevention tips.
- Buy plants from reputable sources.
- Inspect plants before buying.
- Regularly check for infestations.
- Never use garden soil instead of potting compost as it may contain weed seeds, pests, or diseases.
- Avoid leaving dead flowers and leaves around plants.
- Check root balls for soil pests when plants are being repotted.
- Never use infected plants as propagation material.
Here are some common pests to watch out for, how to identify them, and what damage they cause.
Aphids: also known as greenﬂy, aphis, and aphides, they are the main pests of houseplants. These small, usually green, sap-sucking insects infest ﬂowers, shoot tips, and soft leaves, sucking sap and causing mottling and distortion. They also excrete honeydew, which attracts ants and encourages the presence of a fungal disease called sooty mold.
Cyclamen mites: these infest a wide range of plants, including cyclamen, pelargoniums, saintpaulias (African Violets) and impatiens (Busy Lizzies). They are minute, eight-legged, spider-like creatures that cluster on the undersides of leaves. They suck sap, causing leaves to crinkle and darken. Flowering is shortened and buds become distorted and may fall off.
Mealy bugs: white, waxy, woodlice-like creatures that live in groups and especially infest ferns, palms, azaleas, and hippeastrums. They suck sap, causing distortion, loss of vigor, and yellowing of leaves. They excrete honeydew, which encourages the presence of ants and sooty mold.
Red spider mites: also known as greenhouse red spider mites, they are spider-like, minute, usually red, and have eight legs. They suck leaves, causing mottling and, if the infestation is severe, webs. These are unsightly, reduce air circulation around the plant, and make eradication difﬁcult.
Scale insects: swollen, waxy-brown discs, usually static, under which female scale insects produce their young.
Thrips: these tiny, dark brown, ﬂy-like insects jump from one plant to another. They pierce leaves and ﬂowers, sucking sap and causing silvery mottling and streaking. Undersides of leaves develop small globules of a red liquid that eventually turns black.
Vine weevils: serious pests in the adult form, when young, and as larvae. Adults are beetle-like, with a short snout. They chew all parts of plants. The larvae—fat, legless, and creamy white with brown heads—inhabit compost and chew roots.
Whiteﬂy: small, moth-like white insects that ﬂutter from one plant to another when disturbed. They have a mealy or powder-like covering and are mostly found on the undersides of leaves, sucking sap, causing distortion, and excreting honeydew, which encourages the presence of ants and sooty mold.
Non-Chemical Control of Pests and Diseases
Apart from growing plants healthily, with adequate moisture, food, and circulation of air, there are other ways to keep them healthy and to ward off pests and diseases.
- Mist plants with clean water where there is a risk (or presence) of red spider mites.
- Regularly remove dead leaves and ﬂowers.
- Use insecticidal soaps, which are ideal against a wide range of insects and mites.
- Investigate biological controls, which means using other insects and mites to control pests. Biological controls exist for aphids, caterpillars, mealy bugs, soft scale insects, red spider mites, thrips, vine weevil larvae, and whiteﬂies. Ask your garden center for advice.
Reprinted with permission from Houseplant Handbook: Basic Growing Techniques and a Directory of 300 Houseplants by David Squire© 2017. Published by Fox Chapel Publishing. Photography courtesy of Fox Chapel Publishing.
About the Author
David Squire studied botany and horticulture at the Hertforshire College of Horticulture and the Royal Horticulture Society’s Garden at Wisley, England, where he gained the Wisley Diploma in Hotriculture and was awarded an NK Gould Memorial Prize for his collection of herbarium specimens. He has written more than 70 gardening books, which have been sold throughout the world and translated into several languages.
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