Scale Insects on Monstera — Identification and Elimination
Monstera (Monstera deliciosa)
Symptoms
- brown bumps on stems
- bumps on leaves
- sticky honeydew
- sooty mold
- crusty dots on stems
- scale insects
Causes
Introduction from infested plants
Scale insects (order Hemiptera, families Coccidae and Diaspididae) are almost always brought in on plants from nurseries or garden centers. Their hard or waxy outer covering (which gives them their name) makes them easy to overlook during a quick inspection. Juvenile crawlers — the mobile stage before they settle and develop their protective covering — are microscopic and easily transferred between plants.
Weakened plant defenses
Healthy Monstera plants can mount some chemical defense against scale infestations. Plants stressed by overwatering, poor light, or nutritional deficiency have reduced defensive capacity and are easier for scales to colonize successfully.
How to Fix It
- 1
Identify the type of scale: soft scales (family Coccidae) have a waxy but not hard protective layer, are typically brown or tan bumps on stems, and produce honeydew. Armored scales (family Diaspididae) have a harder shield-like covering, do not produce honeydew, and are flatter. Treatment is similar for both but armored scales require more persistent effort because their cover is more impervious to sprays.
- 2
Manually remove individual scales with a soft toothbrush, a cotton swab soaked in rubbing alcohol, or your fingernail. Scrape them off stems and leaf undersides. This physical removal is important because the protective covering resists most spray treatments.
- 3
After manual removal, apply a 70% isopropyl alcohol solution using a cotton ball wiped across affected stems. This kills remaining crawlers and any scales you missed.
- 4
Apply neem oil solution or horticultural oil spray to all plant surfaces. Oil treatments suffocate scales by blocking their spiracles (breathing pores). Ensure complete coverage of stems and leaf undersides.
- 5
Repeat treatment every seven to ten days for six weeks to catch newly hatched crawlers from any eggs that survived the initial treatment.
Prevention
- Inspect stems carefully (use a magnifying glass) when purchasing new plants or before bringing them home
- Quarantine new additions for two to three weeks
- Wipe Monstera stems with a damp cloth monthly — removes crawlers before they can settle and develop protective covers
- Check the undersides of leaves and stem nodes during regular care — scale infestations are much easier to address when caught early
Quick Summary
| Plant | Monstera (Monstera deliciosa) |
|---|---|
| Category | Pests |
| Likely causes | Introduction from infested plants, Weakened plant defenses |
| Fix steps | 5 steps — see above |