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Siberian Larch · Larix sibirica

What are these bugs on my Siberian Larch?

Pests can quickly damage the foliage of your larch, making it look sickly and thin. The most common culprit is the larch casebearer, which hides inside tiny cases on the needles. Check the needles closely for small, cigar shaped structures.

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

Check these first

  1. Look for tiny brown cases on the needles.
  2. Check the undersides of needles for small insects.
  3. Look for sticky residue on the branches.

Likely causes

  1. Larch casebearer

    Most likely

    How to tell: You will see small, brown, cigar shaped cases attached to the needles. The needles themselves will look mined out and turn brown.

    What to do: Prune away heavily infested branches if the tree is small. For larger trees, apply a dormant oil spray in early spring to kill overwintering larvae.

  2. Aphids

    Possible

    How to tell: You might notice sticky honeydew on the needles or ants crawling on the branches. The needles may appear curled or stunted.

    What to do: Spray the needles with a strong stream of water to knock the aphids off. If the infestation persists, use insecticidal soap once a week for three weeks.

When to worry

Small numbers of pests are usually manageable, but a heavy infestation can weaken the tree significantly. If the needles are turning brown over a large portion of the tree, take action immediately.

Stopping it coming back

Maintain tree health with proper watering and annual inspections. A healthy, vigorous tree is much better at resisting pest attacks.

Not sure which one it is? Photograph your siberian larch.

This page lists the usual causes. Pocket Botanist looks at your actual leaf 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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Questions people ask

Will the casebearer kill my tree?
It rarely kills a mature tree, but it can cause severe needle loss and weaken the plant. Young trees are more vulnerable and need closer monitoring.
Do I need to use harsh chemicals?
Usually not. Horticultural oils and insecticidal soaps are effective and much safer for the environment than systemic pesticides.

More problems with Siberian Larch

Back to the Siberian Larch guide

This article was generated with AI from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.