Question to the Department for Environment, Food and Rural Affairs:

To ask His Majesty's Government what assessment they have made of the elm zigzag sawfly in the UK; and what mitigating measures can be taken to slow its spread.

We have a dedicated programme of risk and horizon scanning, which continuously and proactively assesses emerging threats to plant health and the potential impact on the UK.

A comprehensive pest risk analysis for Elm zig-zag sawfly (Aproceros leucopoda) was conducted in 2016, before the pest was first reported in the UK. This is available to view on the published UK Plant Health Risk Register and is attached to this answer, it provides the basis for the inclusion of the pest on that national prioritisation tool.

The assessment concluded that there were no practical options to ensure continued exclusion or eradication from the UK due to its rapid expansion across Europe and the pest being a hitchhiker, which can be introduced on transport such as cars and trains. On that basis, statutory eradication action against findings in the wider environment when the pest was confirmed in the UK in 2017 were not technically justified.

The Forestry Commission conducts ongoing surveillance to monitor the distribution of Elm zig-zag sawfly and have published guidance for landowners to inform its management. Pest spread has also been recorded through citizen science, by the Observatree volunteer network.