AFBI offers guidance on tackling leatherjacket issues in affected grassland
Date published:
Bare patches in grassland this spring could be a sign of leatherjackets. These legless, grey-brown cylindrical grubs are the larvae of crane flies, also known as daddy long-legs. Feeding on grass roots and stems throughout the winter, the damage is now becoming apparent. With chemicals no longer being available, longer term management approaches offer the best solution.
Grassland covers 92% of the utilised agricultural area in Northern Ireland and is the principal and cheapest feed for the ruminant livestock sector. The destruction of grass by leatherjackets can therefore have a significant impact on the profitability of dairy, beef, and sheep farms.
Previous farmer focused work led by AgriSearch and supported by AFBI, helped gather evidence on non‑chemical approaches to managing leatherjacket infestations. This research found the pest to be widespread, with some Fermanagh fields carrying populations of up to 5.5 million per hectare. In 2023, 35% of surveyed fields exceeded the economic threshold of 1 million larvae per hectare.
With older chemical controls no longer available, farmers are encouraged to plan ahead and take an ‘integrated pest management’ approach to grassland management. Liming acidic soils to promote good grass growth, improving drainage, regular reseeding, and regular monitoring of fields to detect potential leatherjacket problems at an early stage are all important measures.
Multi-species swards and brassica break crops can also play a role by helping to ‘break’ the generational cycle of the pest, while providing alternative grazing options. In addition, birds and parasitic wasps contribute to natural control, and there is some evidence that tight grazing in late summer or autumn may reduce egg-laying sites.
While there is no quick fix, a combination of these measures can help reduce leatherjacket pressure over time.
For further information from AFBI and AgriSearch you can listen to the webinar Leatherjackets in Grassland - The Challenge
Notes to editors:
AFBI is an arms-length body of DAERA delivering research and development, diagnostic and analytical testing, emergency response capability and expert scientific advice for DAERA and other government departments, public bodies and commercial companies in Northern Ireland, and further afield.
AFBI’s Vision is “Scientific excellence delivering impactful and sustainable outcomes for society, economy and the natural environment”.
AFBI’s Purpose is to deliver trusted, independent research, statutory & surveillance science, and expert advice that addresses local and global challenges, informs government policy and industry decision making, and underpins a sustainable agri-food industry and the natural and marine environments.
AFBI’s strategic priorities:
- Leading improvements in the agri-food industry to enhance its sustainability;
- Protecting animal, plant and human health;
- Enhancing the natural and marine environment;
- Delivering quality outcomes and impact;
- Enabling world class science through excellence in people, places & technology.