Skip to content
Pocket Botanist
Get the app

Sessile oak · Quercus petraea

What are these pests on my Sessile oak?

Sessile oaks can attract various insects, most notably the oak processionary moth. Look for silk nests or caterpillars on the branches.

Not sure it's this? Check a photo of your plant for free

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

Check these first

  1. Look for silk nests in the branch crotches.
  2. Check the undersides of leaves for small insects.
  3. Observe if leaves are being eaten or skeletonized.

Likely causes

  1. Oak processionary moth

    Most likely

    How to tell: You will see white silk nests on the trunk or branches and lines of caterpillars. These caterpillars have long white hairs that are dangerous to touch.

    What to do: Do not touch them. Contact a professional tree service to remove the nests safely.

  2. Aphids

    Possible

    How to tell: Small green or black insects on the undersides of leaves. They leave behind a sticky substance called honeydew.

    What to do: Spray the leaves with a strong jet of water to knock them off. You can also use insecticidal soap if the infestation is heavy.

Pests on other plants

Find out what's wrong with your sessile oak

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.

Download on the App StoreGet it on Google Play

When to worry

If you see oak processionary moth nests, treat it as a serious health hazard for humans and pets. Minor aphid presence is usually tolerated by mature trees.

Stopping it coming back

Encourage natural predators like ladybugs and birds to visit your garden. Monitor your tree closely during the spring months.

Sessile oak: pests? Check yours with a photo

Every plant is a little different. Take a photo of your sessile oak 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.

Download on the App StoreGet it on Google Play

Get the app · Or check it from a photo now, free

Questions people ask

Are the caterpillars harmful to me?
Yes, the hairs on oak processionary moth caterpillars can cause severe skin rashes and respiratory issues.
Should I use pesticides?
Avoid broad spectrum pesticides as they kill beneficial insects too. Use targeted methods for specific pests.

Guides to these causes

More problems with Sessile oak

Back to the Sessile oak 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.