Sticky leaves, cottony clusters, and sap-sucking pests
A shiny, sticky coating on leaves or nearby surfaces, white cottony tufts in leaf joints, or small clustered insects on stems all point to sap-sucking pests: aphids, mealybugs, and scale insects. They feed on plant sap, weaken growth, and their sticky honeydew can grow sooty mould on top of the damage.
Mealybugs hide in joints and crevices, aphids cluster on soft new growth, and scale insects sit still like small bumps. All three spread easily to neighbouring plants, so isolation comes first, before any treatment.
General beginner information only — not a substitute for advice from your local agricultural extension service. For edible plants, use only a product that is labelled for that particular edible crop, for indoor use, and follow any harvest interval on its label; try non-chemical steps first, and never use a product that is not labelled for indoor use on that plant.
Checklist to diagnose
- Is there a sticky coating on leaves, or on the table and floor under the plant?
- Are there white cottony tufts in leaf axils and stem joints, or small brown or white bumps that do not move?
- Are insects clustered on soft new growth, buds, or leaf undersides?
- Is growth stunted, curled, or dropping leaves beyond what water and light explain?
- Are neighbouring plants showing the same sticky coating or clusters?
Rescue steps
- Isolate the plant immediately so crawlers cannot reach neighbours, and check every nearby plant.
- For small numbers of mealybugs, dab each cluster with a cotton swab dipped in rubbing alcohol, testing on a small area first to check the plant tolerates it; remove scale insects by gentle picking or scrubbing.
- Rinse the foliage to remove honeydew and loose insects, and prune out the most heavily infested growth with clean scissors if the plant can spare it.
- If non-chemical steps are not enough, use a product labelled for indoor use on that plant and for that pest, follow its label exactly, and repeat only as the label directs — one spray rarely ends an infestation because eggs keep hatching.
- Keep checking weekly for several weeks after the plant looks clean; mealybugs and scale in particular hide in crevices and return.
When to give up
- Infestation returns after repeated isolation and treatment, and the plant keeps losing growth faster than it makes it.
- The plant is heavily infested and sits among many others you cannot afford to expose — removing it protects the rest.
Plants on this site
These plant guides on this site already mention this problem: