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Crown of Thorns · Euphorbia milii

What are these bugs on my Crown of Thorns?

Crown of Thorns can attract common houseplant pests that hide in the crevices of their thorny stems. Catching these early is key to keeping your plant thriving. Check the undersides of leaves and the joints of the stems for signs of activity.

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

Check these first

  1. Inspect the joints where leaves meet the stem.
  2. Look for fine webbing near the thorns.
  3. Wipe the leaves with a damp cloth to see if bugs come off.

Likely causes

  1. Mealybugs

    Most likely

    How to tell: You see white, cottony masses tucked into the leaf axils or along the stems.

    What to do: Dip a cotton swab in rubbing alcohol and dab it directly onto the bugs. Repeat this every 5 to 7 days until they are gone.

  2. Spider Mites

    Possible

    How to tell: Tiny yellow stippling on the leaves and very fine webbing between the thorns.

    What to do: Wipe the leaves down with a damp cloth to remove the mites. You can also use insecticidal soap once a week for 3 weeks to clear the infestation.

Pests on other plants

Find out what's wrong with your crown of thorns

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

Pests are manageable if caught early. If the plant is covered in webbing or the leaves are turning yellow and falling off, the infestation is severe.

Stopping it coming back

Keep your plant healthy with proper light and water, and inspect it regularly when you water.

Crown of Thorns: pests? Check yours with a photo

Every plant is a little different. Take a photo of your crown of thorns 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 these bugs harmful to me?
Mealybugs and spider mites are not harmful to humans, but the sap of the Crown of Thorns can be irritating, so wear gloves.
Should I isolate my plant?
Yes, move the infested plant away from your other plants immediately to prevent the pests from spreading.

Guides to these causes

More problems with Crown of Thorns

Back to the Crown of Thorns 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.