Plant care guide
Scale on Monstera Deliciosa: Find It, Scrape It, Treat It
Updated
Why does my Monstera deliciosa have scale?
Immobile tan, brown or white bumps along the veins, on the leaf undersides or on the leaf stalks of a Monstera deliciosa are scale insects. Brown soft scale leaves sticky honeydew; fern scale leaves no honeydew but shows as white flecks of male scales as numbers rise.
What to do first
Isolate the plant, scrape every scale off with a fingernail, toothpick or soft toothbrush, and wipe both sides of each leaf. Follow with horticultural oil or insecticidal soap labeled for houseplants, repeated over several weeks, and inspect new leaves as they unfurl.
Brown bumps along a Monstera’s veins can look like part of the leaf until you notice the stickiness. UW–Madison Extension says Monstera has few pests indoors but lists scale insects among them. UW–Madison describes the leaves as glossy and leathery. That surface is easy to inspect and wipe, so a careful clean-up goes a long way.
Confirm it is scale
Clemson HGIC’s houseplant pests factsheet describes scale adults as small, immobile and legless. Some are flat like fish scales; others look like waxy masses. University of Maryland Extension lists Monstera as a host of two indoor species (UMD: Scale Insects on Indoor Plants):
| Clue | Brown soft scale | Fern scale (armored) |
|---|---|---|
| Look | Oval, tan to yellow-brown, often mottled, up to about 5 mm (3/16 in) | Females flat, oyster-shell shaped, brown; males small, white and ridged |
| Where | Along veins, leaf undersides, leaf stalks, young stems | Mostly on foliage |
| Honeydew | Yes; sticky leaves, possible sooty mould | No |
| Telltale sign | Sticky film on leaves or the floor below | White flecking as male scales multiply |
NC State Extension’s fern scale factsheet also lists Monstera as a host and notes the brown females are often overlooked.
UMD says scale flakes off with a fingernail, toothpick, cotton swab or soft toothbrush. A natural blemish does not.
Where to look on a Monstera
- Along the main veins on the underside of each leaf.
- On the leaf stalks, and at the joint where the blade meets the stalk. NC State describes this junction as distinct on Monstera deliciosa.
- In the sheath of the newest leaf. UMD notes brown soft scale can hide in crevices between emerging leaves, and that its sticky honeydew can deform or tear delicate new growth as it unfurls.
What to do
- Isolate the plant. UMD advises quarantining plants with scale.
- Scrape off the adults. Work along every vein, stalk and stem. UMD notes that removing them also makes any rebound easier to see.
- Wipe both sides of every leaf. Clemson suggests wiping upper and lower surfaces of large plants with a soft, wet cloth, or rinsing them in a tepid shower. Support each leaf with your other hand.
- Prune badly infested leaves. Bag them.
- Treat for crawlers. Clemson says adults are protected by their waxy cover, while the mobile young crawlers are susceptible to insecticidal soap and oils. UMD lists horticultural oil, insecticidal soap, or a systemic labeled for indoor plants. Test on one leaf first.
- Match the product to the scale. Colorado State Extension says oils are the most effective treatment for armored scales such as fern scale, and systemics give them poor control (CSU: Managing Houseplant Pests). UMD notes systemics work on brown soft scale only.
- Repeat. UMD says multiple treatments are usually needed. Colorado State says coverage should continue for two to four months.
Colorado State also warns that scales killed by soap or oil can stay attached and look alive. Judge progress by clean new leaves and no fresh stickiness. UMD advises discarding heavily infested plants.
Handle it safely
The ASPCA lists Monstera deliciosa as toxic to dogs and cats because of insoluble calcium oxalates. UW–Madison notes all parts except the ripe fruit are poisonous. Wear gloves when pruning, and keep trimmings away from pets.
Prevent a return
- Wipe the leaves regularly. NC State advises wiping dust off Monstera leaves; it is also your scale check.
- Quarantine new plants. Clemson suggests six weeks apart, checking leaf undersides weekly.
- Inspect new plants thoroughly. UMD says brown soft scale and fern scale both occur worldwide and can arrive on plant shipments.
Our scale insects guide compares scale types and treatments across houseplants. Cotton-like tufts instead of bumps point to mealybugs; silvery streaks point to thrips on Monstera. More care pages are on the Monstera deliciosa hub.
Related guides
Other monstera deliciosa problems we cover: no fenestration, moldy soil, transplant shock, leggy growth, slow growth.
References
- University of Maryland Extension: Scale Insects on Indoor Plants
- NC State Extension: Fern Scale Insect
- UW–Madison Extension: Swiss-Cheese Plant, Monstera deliciosa
- NC State Extension Gardener Plant Toolbox: Monstera deliciosa
- Clemson Cooperative Extension HGIC 2252: Common Houseplant Insects & Related Pests
- Colorado State University Extension: Managing Houseplant Pests
- ASPCA Animal Poison Control: Cutleaf Philodendron (Monstera deliciosa)
How this guide was put together: University of Maryland Extension, NC State Extension, UW–Madison Extension, Clemson Cooperative Extension, Colorado State University Extension and ASPCA guidance.