Mealybugs are common insects on houseplants and in greenhouses. Mealybugs weaken plants by feeding on the sap, leaving behind a sticky substance (honeydew) on leaves and stems.
What do they do?
Mealybugs live together in clusters, feeding on the sap of plant stems and leaves. They are usually tucked in to the more inaccessible areas of a plant, such as between twining stems or under bark. While they feed on a plant, they excrete a honeydew, which lands on the plant around and below them. This substance encourage sooty mould to form, crating a blackened appearance to leaves.
- Infestations are first noticed as a fluffy white wax. This can usually be found in leaf axils or other sheltered places on the plant. The insects or their orange-pink eggs can be found underneath this substance.
- Sticky, clear substance (honeydew) on leaves, stems and fruit.
- Reduction of plant vigour and stunted growth. Some infestations can cause premature leaf fall.
How to treat
- The female mealybug does not fly or crawl far, so the insects are usually brought in on an infected plant. Inspect new plants carefully and, where possible, keep them in quarantine for at least a month.
- Dead leaves and pruning should be removed as these may have mealybugs or eggs on them.
- It can be sometimes be easier to dispose of heavily infested plants rather than try to eliminate mealybugs.
- Encourage natural enemies (certain ladybirds and parasitic wasps)
Many insecticides can be used to counter the effects of mealybugs, always make sure you read the label before applying. Plants in flower should not be sprayed due to the danger to pollinating insects, such as bees. We recommend: