Berberis sawfly

Berberis sawfly probably became established in south-east England in about 2000, although it was not confirmed until 2002. It has since spread throughout most of England. It is the only insect that feeds on Berberis, likely to cause severe defoliation.

Berberis sawfly larvae.

Quick facts

Common name Berberis sawfly
Latin name Arge berberidis
Plants affected Berberis, especially B. thunbergii, and Mahonia
Main symptoms Leaves are eaten by caterpillar-like larvae. Plants may be completely defoliated
Caused by Caterpillar-like larvae of a sawfly
Timing May-October

What is berberis sawfly?

Creamy white, spotted caterpillar like larvae with black heads feed on the foliage of Berberis and Mahonia often causing severe defoliation. This species of sawfly will only attack these two plants.


Seen berberis sawfly? We would like to know.

As part of our research the RHS would like to know where berberis sawfly has been seen.

Please submit your records via our berberis sawfly survey (expected time to complete survey = two minutes. The RHS confirms that your information will be stored in compliance with the Data Protection Act and your address will not be shared with third parties, other than for data processing purposes. If you prefer not to have your information used in this way, please indicate when submitting your record.).

Thank you to everyone who has submitted records so far – read a blog about the surveys 

Watch an animated map of the results from the berberis sawfly survey (links to YouTube) -



Plants attacked by berberis sawfly are easy to spot:

  • Branches or the whole plant can be defoliated, berberis sawfly is the only insect likely to cause such severe defoliation
  • On closer inspection, black-headed, creamy white caterpillar-like larvae with black spots and orange yellow blotches may be seen feeding on the foliage
  • The adults are shiny black insects, up to 8mm long, with greyish-black wings. They appear similar to many other species of sawfly
  • Sawfly larvae on plants other than Berberis or Mahonia will be a different species, see links below for other common garden sawflies


Non-chemical control

Check plants regularly between late April and October for the presence of larvae. Hand removal may not be possible due to the spines on the stems of berberis.

If a plant is repeatedly attacked consider replacement with a non-susceptible alternative.

Chemical control

  • If infestations are too heavy for hand picking, control may be achieved by spraying with pesticides. Spaying at dusk is likely to give the best results
  • Organic pesticides, such as those containing pyrethrum (e.g. Bug Clear Gun for Fruit and Veg, Defenders Bug Killer, ecofective Bug Killer) will control young larvae but larger larvae are more tolerant of these insecticides
  • Synthetic pesticides containing deltamethrin (e.g. Sprayday Greenfly Killer, Provado Ultimate Bug Killer), lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), cypermethrin (e.g. Py Bug Killer) or the systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) may give some control of larger larvae
  • Plants in flower should not be sprayed due to the danger to pollinating insects
  • Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener


Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)


Berberis sawfly adult
Berberis sawfly distribution
    Berberis sawfly adult Berberis sawfly distribution


    There are two generations of berberis sawfly during the summer and there may be a third generation in autumn.

    The adult sawflies are 7-9mm long and are shiny black with darkened wings. The antennae are characteristically swept upwards.

    Eggs are inserted under the epidermis on the underside of leaves in batches of up to seven. These hatch into caterpillar-like larvae that proceed to devour the foliage.

    When fully grown the larvae are up to 18mm long. They go into the soil to pupate within silk cocoons. This pest overwinters in the ground as pupae.

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