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