Scale Insects on Chinese Evergreen — Found on Stems and Leaf Undersides
Chinese Evergreen (Aglaonema commutatum (and related cultivars))
Symptoms
- small rounded brown or gray bumps on the stem or leaf midribs
- sticky honeydew residue on leaf surfaces
- sooty mold (black) growing on honeydew
- a plant in general decline with no obvious care problem
Causes
Soft or armored scale colonizing the stem and midribs
Scale insects settle onto the stem and the undersides of leaf midribs on Chinese Evergreen, where they become immobile adults and feed indefinitely. Hemispherical scale (Saissetia coffeae) and brown soft scale (Coccus hesperidum) are the species most commonly encountered. They introduce from newly acquired plants or from other infested plants in a collection. Soft scale produces honeydew actively and is typically noticed via the sticky residue on lower leaves before the insects themselves are seen.
How to Fix It
- 1
Chinese Evergreen's stem is usually short and mostly hidden by the low, tight leaf canopy, so start by parting the leaves down to the base rather than scanning from a distance — this is where a first colony tends to sit undetected the longest.
- 2
Scrape each bump loose with a soft toothbrush, working from the crown down toward the soil line rather than up — this pushes dislodged scale away from the growing tip instead of across it.
- 3
Follow with a cotton ball soaked in 70% isopropyl alcohol over the same area. Because Aglaonema's compact form means every stem is within easy reach, plan on a full alcohol pass every 10 days for 6 weeks rather than spot-checking a few stems.
- 4
A neem oil mist, diluted around 2 teaspoons to the quart, over the whole plant closes out the treatment — focus extra passes on the underside of the lowest leaves closest to the stem, since that's where crawlers migrating off a treated stem land first.
Prevention
- Inspect the stem of Chinese Evergreen monthly
- Quarantine new plants before placing near established collection
Quick Summary
| Plant | Chinese Evergreen (Aglaonema commutatum (and related cultivars)) |
|---|---|
| Category | Pests |
| Likely causes | Soft or armored scale colonizing the stem and midribs |
| Fix steps | 4 steps — see above |