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Sawfly

Pest

Sawflies are small, wasp like insects whose larvae look like caterpillars and feed voraciously on plant foliage. They can quickly strip a plant of its leaves, which weakens the plant and ruins its appearance.

Sawfly on a plant
Photo: Kostas Zontanos, CC BY

Symptoms by part

Leaves

You will see small holes, skeletonized patches where only veins remain, or entire leaves consumed starting from the edges.

Causes

  • The presence of adult sawflies laying eggs on the undersides of leaves during the growing season.
  • Warm temperatures that speed up the hatching and development of the larvae.

Could be confused with

  • Caterpillars · Sawfly larvae usually have more than five pairs of prolegs, while most moth or butterfly caterpillars have five or fewer.
  • Beetle larvae · Beetle larvae often have a more distinct head and lack the fleshy prolegs found on sawfly larvae.

Treatment

  1. 1. Handpick the larvae off the leaves early in the morning when they are most active.
  2. 2. Knock the larvae off the foliage into a bucket of soapy water to kill them.
  3. 3. Prune away heavily infested stems or leaves to reduce the population.
  4. 4. Apply spinosad to the foliage if the infestation is widespread, follow the label.

Without chemicals

  • Handpicking larvae.
  • Pruning infested foliage.
  • Encouraging natural predators like birds and parasitic wasps in the garden.

Chemical options

  • Spinosad, apply as a spray to the foliage, follow the label.

Preventing it

  • Keep the area around your plants clear of debris where adults might overwinter.
  • Use fine mesh netting over susceptible plants early in the season to prevent adults from laying eggs.
  • Check the undersides of leaves for clusters of eggs and remove them before they hatch.

Season

The warm growing season.

Spread risk

Moderate

Severity

Moderate

When to act

Act as soon as you spot the larvae or the first signs of leaf damage. If the plant is completely defoliated and fails to recover after a full season, it is best to remove it.

Think it's Sawfly?

This guide covers the general picture. Pocket Botanist looks at your actual plant from a photo and tells you what's really going on, how serious it is, and what to try first. Identification and a health check are free.

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Questions people ask

Are sawfly larvae actually caterpillars?
No, they are the larvae of a type of wasp, though they look very similar to caterpillars.
Will my plant die from a sawfly infestation?
Usually not, but a heavy infestation can severely stress the plant and reduce its vigor for the following year.
Do I need to treat the soil?
No, sawflies spend their life cycle on the foliage or in the soil as pupae, but soil treatment is generally ineffective and unnecessary.

Plants it affects

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This guide was generated with AI and is general information, not horticultural advice. Read about how we build these guides.