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St. John's wort · Hypericum perforatum

What are the bugs on my St. John's wort?

It is less common for this plant to have pests, but aphids or spider mites can occasionally appear when the plant is stressed. Check the undersides of the leaves for tiny insects or webbing first.

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

Check these first

  1. Inspect the undersides of the leaves.
  2. Look for sticky residue on the stems.
  3. Check for fine webbing between leaves.

Likely causes

  1. Aphids

    Most likely

    How to tell: You will see small green or black insects clustering on new growth or flower buds. They often leave behind a sticky substance called honeydew.

    What to do: Wash the aphids off with a gentle stream of water from a hose. If they persist, apply insecticidal soap once a week until they are gone.

  2. Spider Mites

    Possible

    How to tell: Look for fine, silky webbing between the leaves or stems. The leaves may also appear speckled or pale.

    What to do: Increase the humidity around the plant by misting it or moving it away from dry vents. Wipe the leaves down with a damp cloth to remove the mites.

Pests on other plants

Find out what's wrong with your st. john's wort

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 you see large colonies of insects or the plant starts losing leaves, take action immediately. A few stray bugs are usually manageable with simple cleaning.

Stopping it coming back

Keep your plant healthy with proper light and water to make it less attractive to pests.

St. John's wort: pests? Check yours with a photo

Every plant is a little different. Take a photo of your st. john's wort 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

Do I need to use harsh chemicals?
No, you should avoid harsh chemicals. Water sprays and insecticidal soap are usually enough to handle these pests.
Will these bugs kill my plant?
They rarely kill a healthy plant, but they can weaken it over time. Treat them early to keep your plant growing strong.

Guides to these causes

More problems with St. John's wort

Back to the St. John's wort 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.