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Cactus

What are these white fuzzy spots on my cactus?

Those white, cottony spots are likely mealybugs, which are tiny pests that suck the sap from your cactus. They love to hide in the crevices between spines.

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pests on a plant
Photo: Jules Verne Times Two, CC BY-SA 4.0

Check these first

  1. Look closely at the crevices for white cottony webs.
  2. Check nearby plants for signs of the same pests.
  3. Wipe a spot with alcohol to see if the white mass dissolves.

Likely causes

  1. Mealybug Infestation

    Most likely

    How to tell: You see small white, cottony masses on the surface of the cactus. The plant may look stunted or lose vigor.

    What to do: Dip a cotton swab in rubbing alcohol and dab it directly onto the white spots to kill the bugs. Repeat this every few days until they are gone.

  2. Poor Air Circulation

    Possible

    How to tell: The plant is in a very stagnant, humid corner with no airflow. Pests thrive in these conditions.

    What to do: Move your cactus to a spot with better airflow. Ensure it gets plenty of direct sunlight to keep the plant healthy and resistant.

Pests on other plants

Find out what's wrong with your cactus

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.

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When to worry

If the infestation covers the entire plant, it can be very difficult to clear. Treat it as soon as you see the first white spot.

Stopping it coming back

Inspect your cactus regularly when you water it. Keeping the plant in bright, direct sun helps it stay strong against pests.

Cactus: pests? Check yours with a photo

Every plant is a little different. Take a photo of your cactus 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

Will these bugs kill my cactus?
If left untreated, they can weaken the plant significantly. They drain the sap and can lead to secondary infections.
Can I use soap to kill them?
You can use a mild insecticidal soap, but rubbing alcohol is usually more effective and safer for the cactus skin.

Guides to these causes

More problems with Cactus

Back to the Cactus guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.