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Berberis sawfly became established in south-east England in about 2000, although it was not detected until 2002. It has since spread throughout most of England. It is the only pest of 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).
Thank you to everyone who has submitted records so far – read a blog about the surveys
Was 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.
Organic pesticides, such as pyrethrum (e.g. Bug Clear Gun for Fruit and Veg, Defenders Bug Killer, Pyrol Bug & Larvae Killer) will control young larvae but larger larvae are more tolerant of these insecticides.
Heavy infestations can be sprayed with deltamethrin (e.g. Bayer Sprayday Greenfly Killer, Bayer Provado Ultimate Bug Killer), lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), cypermethrin (e.g. Py Bug Killer) or the systemic insecticide acetamiprid (e.g. Bug Clear Ultra).
Plants in flower should not be sprayed due to the danger to pollinating insects.
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.
Apple sawflyAquilegia sawflyAruncus sawflyGeum sawflies Gooseberry sawflyHedges: selectionIris sawflyLarge rose sawflyRose leaf-rolling sawflyRose slug sawfly or slugwormShrubs: pruning evergreensSolomon's seal sawfly
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Join the RHS today and get 12 months for the price of 9