Common Houseplant Pests & How to Beat Them (UK Edition)
Common Houseplant Pests & How to Beat Them (UK Edition)
Even the most attentive plant parent will encounter pests at some point. The good news? Most houseplant pests are very manageable if you catch them early. The key is knowing what to look for — and acting quickly before they spread to the rest of your collection.
Here's your complete guide to the most common houseplant pests in the UK, how to identify them, and how to get rid of them for good.
🦹 Fungus Gnats
What they look like: Tiny black flies hovering around your soil and flying up when you water. The adults are harmless, but their larvae live in the soil and feed on roots.
Why they appear: Overwatering and consistently moist soil are the main culprits. Fungus gnats love damp compost.
How to treat them:
- Let the top 3–5 cm of soil dry out completely between waterings — larvae can't survive in dry soil.
- Use yellow sticky traps to catch adult flies and monitor numbers.
- Apply a layer of horticultural grit or sand to the top of the soil — this deters females from laying eggs.
- For serious infestations, use a biological control: Steinernema feltiae nematodes (available from UK garden centres) are highly effective and completely safe for plants and pets.
- Neem oil watered into the soil can also help deter larvae.
🕸️ Spider Mites
What they look like: Tiny red or brown dots on the undersides of leaves, often accompanied by fine webbing. Leaves may look stippled, pale, or dusty.
Why they appear: Hot, dry conditions — exactly what UK summers can bring indoors. Spider mites thrive when humidity is low.
How to treat them:
- Increase humidity around affected plants immediately.
- Wipe down leaves with a damp cloth to physically remove mites and webbing.
- Spray with a diluted neem oil solution (follow label instructions) or a specialist spider mite spray.
- For severe infestations, use predatory mites (Phytoseiulus persimilis) — a brilliant biological control available online and in UK garden centres.
- Isolate affected plants immediately to prevent spreading.
💡 Prevention tip: Regularly misting your plants and keeping humidity up is the best defence against spider mites.
🦸 Mealybugs
What they look like: White, fluffy, cotton-wool-like clusters in leaf joints, on stems, and on the undersides of leaves. They move slowly and are easy to spot once you know what you're looking for.
Why they appear: Often introduced on new plants. They spread quickly in warm conditions and can be tricky to fully eliminate.
How to treat them:
- Dab individual mealybugs with a cotton bud soaked in rubbing alcohol (isopropyl alcohol) — this kills them on contact.
- Spray the whole plant with a diluted neem oil solution, paying close attention to leaf joints and undersides.
- Repeat treatment every 5–7 days for at least 3–4 weeks to catch newly hatched eggs.
- Isolate the plant immediately and check all nearby plants carefully.
- For persistent infestations, a systemic insecticide (such as Bug Clear Ultra) can be effective.
🐛 Vine Weevils
What they look like: Adults are dull black beetles about 9mm long with a distinctive snout. But it's the creamy-white, C-shaped grubs in the soil that cause the real damage — they eat roots and can kill a plant seemingly overnight.
Why they appear: Plants moved outdoors in summer are particularly vulnerable, as adult vine weevils are active from spring through autumn.
How to treat them:
- If a plant suddenly collapses despite good care, check the roots immediately — you may find grubs in the soil.
- Remove and destroy any grubs you find by hand.
- Use Steinernema kraussei nematodes — the most effective biological control for vine weevil grubs in UK conditions. Apply to moist soil in late summer.
- Check plants thoroughly before bringing them back indoors after summer.
🐞 Scale Insects
What they look like: Brown, oval, shell-like bumps on stems and the undersides of leaves. They don't move much, which makes them easy to mistake for part of the plant.
How to treat them:
- Scrape off scale insects manually with a soft toothbrush or your fingernail.
- Wipe stems and leaves with a cloth soaked in diluted neem oil or rubbing alcohol.
- Repeat weekly until no new scale appears.
🛡️ Prevention: Your Best Defence
The best way to deal with pests is to stop them before they start:
- Quarantine new plants for 2–4 weeks before introducing them to your collection.
- Inspect regularly — check the undersides of leaves and soil surface when you water.
- Keep plants healthy. Stressed plants are far more susceptible to pest attack. Good light, correct watering, and regular feeding make a real difference.
- Clean your plants. Wipe down leaves with a damp cloth monthly to remove dust and deter pests.
- Check outdoor plants before bringing them back in at the end of summer.
🏆 A Note from Emm's
Dealing with pests can be disheartening, but don't give up on your plants! With the right treatment and a little patience, most infestations can be fully resolved. If you're ever unsure what you're dealing with, drop us a message — we're always happy to help.
Visit us at emmsplanthouse.co.uk and follow us on TikTok for pest ID videos, treatment demos, and plant care tips.
Stay pest-free! 🌿
— The Emm's Plant House Team