Ash Sawfly
The Ash Sawfly (Tomostethus nigritus) is emerging as a significant pest in Northern Ireland, particularly affecting ash trees. It was first identified in Northern Ireland in 2016.
What Is the Ash Sawfly?
Flying adults lay their eggs on the young ash leaves. The larvae of the ash sawfly are olive-green and caterpillar-like, appearing in large numbers during late spring and early summer. They feed aggressively on ash leaves, leaving only the mid-rib of the leaf. While the damage is rarely fatal, repeated infestations can weaken trees and reduce their resilience.
What Can Be Done?
There is currently no recommended chemical control. Instead, experts suggest:
- Manual removal of larvae before they pupate in the soil.
Biosecurity
Good biosecurity can help prevent or limit the spread of pests and diseases.
Want to help protect our trees? Find out what you can do with simple biosecurity
Further Information
Agri-Food and Biosciences Institute (AFBI) have produced a factsheet: