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Onion · Allium cepa

What are these pests on my spring onions?

Spring onions can attract tiny invaders that damage the leaves and bulbs. Look closely at the leaves and the soil surface to identify what is bothering your plant.

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

Check these first

  1. Look for tiny insects on the leaves.
  2. Check the base of the plant for signs of tunneling.
  3. Inspect the leaves for silvery streaks.

Likely causes

  1. Thrips

    Most likely

    How to tell: You see tiny insects and silvery streaks or distorted growth on the leaves.

    What to do: Spray the leaves with insecticidal soap or neem oil every 5 to 7 days. Make sure to cover the undersides of the leaves.

  2. Onion Maggots

    Possible

    How to tell: The plant wilts suddenly and you find small white maggots tunneling into the bulb.

    What to do: Remove and destroy infested plants immediately to prevent the cycle from continuing. Use row covers early in the season to keep adult flies from laying eggs.

Pests on other plants

Find out what's wrong with your onion

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 maggots in the bulb, the plant is usually lost. Thrips are manageable if caught early.

Stopping it coming back

Use row covers to block pests and rotate your planting site if growing in the ground.

Onion: pests? Check yours with a photo

Every plant is a little different. Take a photo of your onion 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 pests harmful to humans?
No, thrips and onion maggots are not harmful to humans, but they will ruin the quality of your harvest.
Can I wash the pests off?
A strong spray of water can dislodge thrips, but it will not eliminate an infestation. You will likely need an insecticidal soap.

Guides to these causes

More problems with Onion

Back to the Onion 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.