Mealybugs are the white, cottony pests that cluster in the joints and creases of plants, and they are one of the most stubborn pests in the garden — especially indoors, where they have no winter to kill them and few predators to keep them in check. They suck sap, weaken plants, distort growth and leave sticky honeydew that encourages sooty mould. They are also protected by a waxy, cottony coating that repels sprays, which makes them harder to control than aphids. Patience and persistence are the keys.
This guide covers how to identify mealybugs, what damage they cause, how they live, and how to control them organically.
Identifying mealybugs
Mealybugs are small, soft-bodied, oval insects, usually 2–4 mm long, covered in a white, waxy, cottony coating that gives them their name. They cluster in groups, typically in the sheltered places on a plant: in leaf joints, under leaves, in the creases of stems, on the undersides of leaves and around the base of the plant.
Look for:
- White, cottony clusters in leaf joints, stem creases and under leaves
- Small, oval, white insects with a waxy coating, sometimes with short filaments around the edge
- Leaves that yellow, wilt or distort, especially new growth
- Sticky honeydew on leaves, often with black sooty mould growing on it
- Ants on the plant, farming the mealybugs for honeydew
- A general loss of vigour, and in heavy infestations, leaf drop
Mealybugs are sometimes confused with other pests. Scale insects are similar, but they have a hard, shell-like covering and do not move, while mealybugs are soft, cottony and can crawl slowly. Woolly aphids also look cottony, but they are usually found on woody stems and branches rather than on soft growth. If the pest is white, cottony and clustered in leaf joints, it is a mealybug. If you are unsure, our pest identifier helper can help you work through the symptoms, and your local extension service can confirm an identification.
The mealybug lifecycle
Mealybugs reproduce steadily rather than explosively. The female lays hundreds of tiny eggs in a cottony sac, usually in a sheltered place on the plant. The eggs hatch into small, mobile crawlers that spread out over the plant, settle down, and begin feeding. They grow through several stages over a few weeks, then become adults and begin laying eggs themselves.
In warm conditions, the whole cycle can take six to eight weeks, and there may be several overlapping generations at once — eggs, crawlers and adults all present on the same plant. Outdoors, mealybugs are worst in summer and die back in cold weather, though they can survive mild winters in sheltered spots. Indoors, they can remain active all year, which is why they are such a persistent problem for houseplants.
The crawlers are the vulnerable stage: they have not yet developed their full waxy coating, and they are the ones that spread to new plants. The adults are protected by their wax, which repels water and many sprays. This is why control must target the crawlers and must be repeated — a single treatment kills the crawlers but leaves the eggs, and a new generation appears within weeks.
Damage signs
Mealybugs damage plants by sucking sap, which weakens the plant and slows growth. Their feeding distorts new growth — leaves curl, yellow and drop, shoot tips twist, and flowers may fail to open. Their honeydew coats leaves and encourages sooty mould, which blocks light and looks unpleasant. In heavy infestations, the plant may be seriously weakened, and young plants can be killed.
Mealybugs attack a wide range of plants, but they are most common on houseplants — especially succulents, cacti, orchids, citrus and other plants with sheltered leaf joints — and on greenhouse crops such as tomatoes and peppers. Outdoors, they attack fruit trees, ornamental shrubs and some vegetables, though they are less common outdoors in cold climates.
On aloe vera and other succulents, mealybugs hide in the tight joints between leaves, where they are hard to reach. On orchids, they cluster around the flower spikes and the base of the plant. On citrus, they attack the fruit and the new growth, causing fruit drop and distorted leaves.
Organic-first control, in order
Work through these steps in order, starting with the gentlest. Mealybug control takes persistence — expect to repeat the steps for several weeks.
1. Inspect regularly. Check the leaf joints, stem creases and undersides of leaves at least once a week, and more often in warm weather. Use a hand lens if you need to — the early stages are small. Early detection is essential, because a small colony is easy to deal with and a large one is not.
2. Isolate the plant. If a houseplant has mealybugs, move it away from your other plants immediately. The crawlers spread easily, and a single infested plant can infect a whole collection in weeks. Keep it isolated until you are confident the mealybugs are gone — at least a few weeks after the last one you saw.
3. Remove them by hand. For a small infestation, dab each mealybug with a cotton bud dipped in rubbing alcohol (isopropyl alcohol). The alcohol dissolves the waxy coating and kills the insect on contact. This is slow, but it is the most reliable method for a few plants, and it reaches into the creases where sprays cannot. Repeat every few days until you find no more.
4. Spray with water. A strong jet of water knocks mealybugs off the plant, and it is useful outdoors and for large plants. It will not remove all of them — the waxy coating helps them cling — but it reduces numbers and washes off honeydew. Repeat every few days.
5. Prune out badly affected growth. If a stem or a cluster of leaves is heavily infested, cut it off and drop it in a bucket of soapy water or a sealed bag — do not compost it in a cold heap. This removes a whole colony at once.
6. Encourage beneficial insects. Ladybirds, lacewings and parasitic wasps all eat mealybugs, and they are the best long-term control outdoors. In a greenhouse, the ladybird Cryptolaemus — often called the mealybug destroyer — is available from biological control suppliers and is highly effective. Outdoors, plant flowers that attract predators and avoid spraying anything that kills them.
7. Least-toxic sprays, last. If the steps above have not brought numbers down, insecticidal soap or horticultural oil can be used. These work by contact and by smothering, so you must cover the insects directly, especially in the creases and joints where they hide. The waxy coating makes mealybugs harder to kill with sprays than aphids, so you will need to repeat the treatment every five to seven days for at least three weeks to catch each new generation of crawlers as they hatch. Apply in the evening to avoid harming bees and to reduce leaf scorch. Always read and follow the label, use only products approved for the crop in your area, and wash produce before eating. Never use a broad-spectrum insecticide: it kills the predators that control mealybugs.
If you are unsure which product is appropriate, check your local extension service for recommendations in your area.
Prevention
Prevention is mostly about inspection and hygiene. Check new plants carefully before bringing them home or into the greenhouse — mealybugs often arrive on a new purchase, hidden in a leaf joint. Isolate new plants for a week or two and check them before placing them among your other plants.
Keep plants healthy with steady watering and moderate feeding, and avoid overcrowding — good airflow makes plants less attractive. For houseplants, keep them in good light, water steadily and check the leaf joints weekly. See also our guide to fungus gnats, another common indoor pest.
For outdoor plants, clear away old plant material where mealybugs can shelter, and encourage predators by planting flowers and leaving some habitat.
When is it a serious problem vs cosmetic?
A few mealybugs on a large, healthy outdoor plant are cosmetic — pick them off and let predators do the rest. It becomes a serious problem when numbers are high and climbing, when new growth is distorted, when leaves are yellowing and dropping, when honeydew and sooty mould cover the plant, or when a houseplant collection is affected. Indoors, even a small population should be taken seriously, because there are no winters and few predators to keep numbers down, and the crawlers spread easily from plant to plant.
Mealybugs on a single outdoor shrub are a nuisance. Mealybugs spreading through a houseplant collection are a serious problem. The difference is numbers, the setting and the rate of spread — and weekly inspection is how you tell which one you have.
Frequently asked questions
What kills mealybugs instantly? Rubbing alcohol on a cotton bud kills on contact by dissolving the waxy coating. Insecticidal soap also kills on contact. But no single treatment kills the eggs, so you must repeat for several weeks to catch each new generation.
Are mealybugs harmful to people or pets? No. They do not bite people or pets and are not poisonous. They are a plant problem, not a health problem.
Can mealybugs spread to other plants? Yes, easily — the crawlers walk to nearby plants, and they can also be carried on hands, tools and clothing. Isolate infested plants and wash your hands and tools after handling them.
Will mealybugs go away in winter? Outdoors, cold weather kills most of them. Indoors, they remain active all year, so winter is not a break — it is a time to keep inspecting and treating.
Can I use washing-up liquid on mealybugs? It is sometimes recommended as a home remedy, but washing-up liquid is not formulated for plants and can damage leaves, especially in sun. Insecticidal soap, made for the purpose and used at the label rate, is safer and more reliable.
The bottom line
Mealybugs are stubborn because their waxy coating protects them and their eggs hide in creases — so control takes persistence. Inspect weekly, isolate infested plants, dab them with alcohol, encourage predators, and use insecticidal soap only if the gentler steps have not worked, repeating for several weeks. For more pest guidance, see the guides hub and the garden tools.