Are scale insects harmful?

Yes, they suck the nutrients out of your fern and can cause fronds to yellow and drop. They can eventually kill the plant if the infestation is heavy.

Will the sticky residue go away?

Once you remove the pests, you can gently wipe the leaves with a damp cloth to remove the sticky honeydew.

Black spleenwort: pests, causes and fixes

Check these first

Scrape a bump to see if it moves or detaches.
Look for sticky honeydew on the leaves.
Inspect the undersides of all fronds carefully.

Likely causes

Scale Insects
Most likely
How to tell: Small, hard brown bumps that look like part of the plant but can be scraped off with a fingernail. You might also see a sticky residue on the leaves.
What to do: Scrape the insects off gently with a cotton swab dipped in rubbing alcohol. Treat the entire plant with neem oil or insecticidal soap once a week for a month.
Infestation from nearby plants
Possible
How to tell: Pests appearing suddenly after introducing a new plant to your home. Check all neighboring plants for similar bumps.
What to do: Isolate the infected fern immediately to prevent spread. Clean the area where the plant was sitting with soap and water.

Pests on other plants

Find out what's wrong with your black spleenwort

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

When to worry

Scale can weaken the plant significantly if left unchecked. Treat it as soon as you spot the first bump.

Stopping it coming back

Inspect new plants thoroughly before placing them near your fern. Wipe down the fronds occasionally to keep them clean.

Black spleenwort: pests? Check yours with a photo

Every plant is a little different. Take a photo of your black spleenwort and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

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Questions people ask

Are scale insects harmful?: Yes, they suck the nutrients out of your fern and can cause fronds to yellow and drop. They can eventually kill the plant if the infestation is heavy.
Will the sticky residue go away?: Once you remove the pests, you can gently wipe the leaves with a damp cloth to remove the sticky honeydew.

Guides to these causes

Scale Insects

What are these brown bumps on my Black spleenwort?

Check these first

Not sure what's wrong with your black spleenwort?