Treatment Plans
Eliminate mealybugs
Alcohol on a cotton swab, showering and soap: steps to remove mealybugs from a plant and prevent their return.
Mealybugs form white cottony clumps in leaf axils and on stems, making foliage sticky. For reliable identification, see the mealybug guide. The scale insect treatment brings together sourced doses and treatment intervals for all types, including mealybugs.
- General weakening and slower growth.
- Yellowing and premature leaf drop.
- A black, sticky coating (sooty mold) on leaves.
- Distorted new shoots or flowers.
Their bodies are protected by white wax that makes them resistant to many simple contact treatments.
Their life cycle
Their life cycle is rapid, especially in warm interiors, explaining their sudden proliferation. A female can lay 300 to 500 eggs in a protective waxy, cottony sac. The complete cycle can last 30 to 90 days, depending on temperature, with 30 °C (86 °F) ideal for rapid development. One treatment is therefore ineffective.
| Stage | Estimated duration | Detail |
|---|---|---|
| Egg laying | 5–10 days | The female deposits 300 to 500 eggs in a cottony egg sac, then dies. |
| Nymphs (larvae) | Several weeks | Highly mobile initially, they disperse to find feeding sites. This is the most vulnerable stage. |
| Adults | 1–2 months | Females remain relatively immobile, feeding and reproducing. Winged males are very short-lived. |
Winged males live only to mate and do not feed. Females and larvae cause all the damage.
What to do now
- Isolate the infested plant immediately to prevent spread to other plants. Nymphs are highly mobile.
- Remove as many visible mealybugs as possible with a cotton swab or cloth soaked in 70% alcohol or soapy water.
- Shower foliage thoroughly with lukewarm water to dislodge remaining insects and wash off honeydew.
- Prepare a natural insecticidal solution: mix approximately 15 mL (1 US tablespoon) of liquid soft soap and approximately 15 mL (1 US tablespoon) of vegetable oil (rapeseed or olive) into 1 liter (about 1.06 US qt) of water.
- Spray the whole plant, concentrating on leaf undersides and stems. Oil suffocates insects while soap helps dissolve their waxy covering.
- Repeat spraying every 7 days for at least 4 weeks. This eliminates new generations hatching from eggs.
Prevention
- Carefully inspect every new plant before bringing it home.
- Always quarantine new plants for 3 to 4 weeks.
- Examine plants once a week, checking beneath leaves and at stem junctions.
- Avoid excessive nitrogen fertilizer, which encourages tender foliage attractive to mealybugs.
Common problems
- Mealybugs · White cottony clumps in leaf axils and on stems.
FAQ
Where do mealybugs come from?
Most often, they arrive on a **new infested plant**. They may also hide in contaminated potting mix or be carried by air currents or ants farming them for honeydew.
Are mealybugs dangerous to people or animals?
No. Mealybugs are **not dangerous** to people or pets such as dogs and cats. They attack only plants.
What is sooty mold, the black coating on leaves?
Sooty mold is a fungus growing on **honeydew**, a sugary, sticky substance excreted by mealybugs. This black coating does not directly parasitize the plant, but **reduces photosynthesis** by blocking light, weakening the plant.
Why are they so difficult to eliminate?
Their bodies are covered in a **white waxy secretion** that protects against contact insecticides. They also hide in hard-to-reach places such as leaf axils and roots, while their rapid reproductive cycle allows new generations to hatch after a single treatment.
Can I use natural predators indoors?
Yes. Biological control is very effective. The ladybug **Cryptolaemus montrouzieri** specializes in mealybugs and is effective as both larva and adult. Lacewing larvae are another good option. These beneficial insects can be ordered online and suit severe indoor or greenhouse infestations.
Can mealybugs survive in potting mix?
Yes. Some species attack roots. If infestation persists despite foliar treatment, you may need to remove the plant from its pot, clean roots and completely replace the growing medium.