Pocket Botanist
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Check these first
- Shake the stems over a white piece of paper to see if tiny insects fall off.
- Check the flower buds for signs of distortion or webbing.
- Look for sticky residue on the leaves.
Likely causes
Thrips
Most likelyHow to tell: You will notice silvery stippling on the leaves and twisted, stunted growth on the flower spikes.
What to do: Spray the plant with insecticidal soap or neem oil every 5 to 7 days. Make sure to coat the undersides of the leaves where these pests hide.
Aphids
PossibleHow to tell: Look for clusters of tiny green or black insects on the new growth and flower buds.
What to do: Blast the aphids off with a strong stream of water from your hose. If they return, apply a mild horticultural oil.
Find out what's wrong with your purple loosestrife
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.
Scan with your phone's camera to get the app
Or go to pocketbotanist.app/get on your phone
When to worry
Worry if the plant stops blooming or if the leaves start to curl and turn brown. A few insects are normal, but a full infestation needs quick action.
Stopping it coming back
Keep your plant healthy with consistent moisture and check it weekly during the peak growing season.
Purple loosestrife: pests? Check yours with a photo
Every plant is a little different. Take a photo of your purple loosestrife 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.
Scan with your phone's camera to get the app
Or go to pocketbotanist.app/get on your phone
Get the app · Or check it from a photo now, free
Questions people ask
- Are these bugs harmful to other plants?
- Yes, thrips and aphids can easily move to your other garden plants. Isolate the affected purple loosestrife if possible.
- Do I need to use harsh chemicals?
- No, you can usually manage these pests with gentle options like insecticidal soap or neem oil. Avoid broad spectrum pesticides that kill beneficial insects.
Guides to these causes
More problems with purple loosestrife
Back to the purple loosestrife 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.