Even the healthiest houseplants can occasionally attract unwanted visitors. Thrips, spider mites, mealybugs and other common pests can damage leaves, weaken growth and spread to neighbouring plants if left unchecked.
The good news? Most infestations can be managed when detected early. At Plantlovers, we grow tropical plants in our own greenhouses, where monitoring and biological pest control are an important part of our daily routine.
In this guide, we'll help you recognise common houseplant pests, understand how to deal with them and prevent small problems from becoming serious infestations.
1. Prevention: your first line of defence
Keeping pests completely out of your home is difficult, but a few simple habits can significantly reduce the risk of an infestation.
- Inspect your plants regularly. Check the undersides of leaves, new growth, stems and leaf joints. Many pests are easier to spot before they cause visible damage.
- Check new arrivals. Keep new plants separate from your existing collection for a while and inspect them carefully before introducing them.
- Keep your plants healthy. Appropriate light, watering and nutrition help plants maintain healthy growth, although even well-cared-for plants can attract pests.
- Remove dead plant material. Fallen leaves and decaying debris can provide shelter for certain pests.
- Monitor suspicious plants. Sticky traps can help detect flying insects, but they are monitoring tools rather than a complete treatment.
Prevention does not mean creating a perfectly sterile environment. It means paying attention to your plants and noticing changes early.
2. Recognising common houseplant pests
Thrips
Thrips are tiny, slender insects that feed on plant tissue. They can be particularly troublesome because they hide in young leaves and growing points, where damage may develop before the insects become noticeable.
Common signs:
- Monstera and Philodendron: Feeding damage often appears as orange-brown discolouration on the underside of the leaves, showing through as yellow-orange patches on the upper surface.
- Hoya: Damage typically appears as silvery patches or scarring on the leaf surface.
- Distorted or damaged new growth
- Small, elongated insects or larvae
- Tiny dark spots of insect waste
Thrips can be persistent because different life stages may be present in different parts of the plant. Some species also spend part of their development in the growing medium.
What to do: Isolate the affected plant, inspect new growth carefully and remove visible insects where possible. Biological control with suitable predatory mites can help target young thrips larvae. Heavy infestations may require a broader approach.
Spider mites
Spider mites are extremely small arachnids that feed on plant cells. They often thrive in warm, dry conditions and can multiply quickly.
Common signs:
- Fine yellow or pale speckling on leaves
- Gradual fading or discolouration
- Tiny moving dots, especially underneath leaves
- Fine webbing, particularly when populations become established
What to do: Isolate the plant, inspect leaf undersides and gently wash away visible mites where practical. Predatory mites specifically selected for spider mite control can help reduce populations. Continue checking the plant because eggs and newly emerging mites may remain.
Mealybugs
Mealybugs are soft-bodied insects covered in a white, waxy coating. They often gather around leaf joints, stems and sheltered areas of the plant.
Common signs:
- White, cotton-like clusters
- Sticky honeydew on leaves
- Yellowing or weakened growth
- Occasionally, black sooty mould growing on honeydew
What to do: Isolate the plant and carefully remove visible mealybugs with a damp cloth or cotton swab. Inspect hidden areas and repeat checks regularly. Persistent infestations may require an appropriate, targeted treatment.
Scale insects
Scale insects attach themselves to stems and leaves, often appearing as small brown, beige or whitish bumps. Many remain relatively immobile once established.
Common signs:
- Small raised bumps on stems or leaves
- Sticky honeydew from some species
- Yellowing leaves or weakened growth
What to do: Check whether the bumps are insects rather than natural plant markings. Remove accessible scale insects carefully and inspect the plant regularly for new individuals.
Aphids
Aphids are small, soft-bodied insects that commonly gather on tender shoots, developing leaves and flower buds.
Common signs:
- Clusters of small green, black, yellow or brown insects
- Distorted young growth
- Sticky honeydew
- Occasionally, shed insect skins
What to do: Wash or remove visible aphids where practical. Check fresh growth repeatedly, as populations can increase quickly.
Fungus gnats
Fungus gnats are small, dark flies often seen hovering around pots. Their larvae live in moist growing media and feed mainly on fungi and decaying organic matter, although they can damage delicate roots when populations are high.
Common signs:
- Small flies around the potting mix
- Increased activity after watering
- Persistent populations in consistently moist growing media
What to do: Avoid keeping the growing medium unnecessarily wet, while respecting the plant's watering requirements. Yellow sticky traps help monitor adults, and suitable biological controls such as beneficial nematodes can target larvae.
3. What to do when you discover pests
Finding insects on a favourite plant can be frustrating, but there is no need to panic.
Step 1 — Isolate the affected plant. Move it away from healthy plants where practical to reduce the risk of spreading pests.
Step 2 — Identify the problem. Look for the insects themselves, not just the damage. Different pests require different approaches, and leaf discolouration alone is not always enough for a reliable diagnosis.
Step 3 — Reduce the population. Remove visible insects, wash affected leaves when appropriate and remove severely damaged plant material if necessary. Avoid unnecessarily stressing the plant.
Step 4 — Choose a suitable treatment. Depending on the pest and severity, this may involve biological control or a plant-protection product specifically authorised for that use. Always follow the product instructions.
Step 5 — Keep monitoring. Check the plant regularly over the following weeks. Many pests have several developmental stages, so one treatment or inspection may not be enough.
4. Biological pest control: working with nature
Biological pest control uses beneficial organisms that naturally feed on or parasitise plant pests.
In our greenhouses, beneficial organisms form an important part of our pest-management strategy. Rather than relying exclusively on treatments after damage appears, we aim to monitor pest populations and intervene early.
For houseplant enthusiasts, predatory mites are among the most practical biological control options.
Swirskii predatory mites (Amblyseius swirskii) mainly target young thrips larvae and can also feed on certain whitefly stages. They are particularly useful as part of a preventive or early-intervention strategy.
Spical predatory mites (Neoseiulus californicus) target spider mites and can help prevent small populations from developing into serious infestations.
These two beneficial mites have different targets. Swirskii is not a replacement for Spical when dealing with spider mites, and Spical is not the appropriate primary choice for thrips.
Biological control works best when the beneficial organism matches the pest, environmental conditions are suitable and populations are monitored.
5. How do predatory mite sachets work?
Some predatory mites are supplied in small breeding sachets rather than as loose organisms.
These sachets contain predatory mites at different developmental stages, along with feeder mites that provide a food source. This allows the beneficial mites to reproduce inside the sachet and gradually emerge over time.
Hang the sachets in the foliage according to the supplier's instructions. Do not open or squeeze them, and avoid placing them where they will become soaked during watering.
The sachets provide a gradual release of beneficial mites, but they are not an instant solution to a severe infestation.
Temperature, humidity, pesticide residues and the pest population can all influence the results. Always follow the instructions supplied with the specific product.
6. Patience and follow-up
Successful pest control rarely happens overnight.
Even when adult insects disappear, eggs or immature stages may still be present. Some damage also remains visible long after the pests have been eliminated.
Instead of judging the result only by old leaves, pay attention to new growth and look for fresh feeding marks or living pests.
Continue inspecting nearby plants and repeat or adjust your control strategy when necessary.
The goal is not necessarily to eliminate every organism from your indoor environment. It is to prevent pest populations from causing significant damage and keep your plants growing well.
Our advice: Make regular plant inspections part of your care routine. A few minutes of observation can save a great deal of trouble later.
Want to learn more about pest control?
We've written several in-depth articles about common houseplant pests and how to deal with them:
Biological pest control
Looking for a natural way to protect your plants? Discover our predatory mites:
- Swirskii – for young thrips larvae
- Spical – for spider mites
Choose the right beneficial mites for the pest you're dealing with and always follow the product instructions.
