What Are Leatherjackets?
Leatherjackets are the larval stage of crane flies, commonly known as daddy longlegs. These cylindrical, legless grubs—up to 30mm long with a tough, leathery skin—belong to the Tipulidae family, with over 300 species in the UK alone. They burrow into the soil, feeding on grass roots and organic matter, which weakens your lawn and leads to yellowing or dead patches. Unlike other pests, leatherjackets don’t have a visible head, making them tricky to spot until the damage is done.
Causes of Leatherjacket Infestations in UK Lawns
Leatherjacket problems start with their adult form: crane flies lay eggs in moist grass during late summer and autumn (typically August to October). The eggs hatch into larvae within weeks, thriving in damp, poorly drained soils—conditions all too common in the UK’s variable climate.
Key causes include:
- Wet and Mild Winters: Prolonged rain creates ideal hatching environments, allowing larvae to survive and feed through the colder months.
- Compacted or Poorly Aerated Soil: Lawns with heavy clay or foot traffic trap moisture, encouraging egg-laying.
- Organic Matter Build-Up: Thatch layers provide food and shelter for the grubs.
- Environmental Factors: Milder temperatures due to climate shifts reduce natural die-off, leading to higher survival rates.
If your lawn has suffered from waterlogging or neglect, it’s prime real estate for these pests. Early detection is key—look for birds like starlings or crows pecking at your grass, as they’re often hunting for leatherjackets.
Trends in Leatherjacket Infestations Across the UK
In 2025, leatherjacket infestations are on the rise, fuelled by record wet winters and shifting weather patterns. Experts warn that damp conditions have created “perfect environments” for crane flies to thrive, with reports of increased activity in regions like the Midlands, South East, and Scotland.
Recent trends show:
- Climate Impact: Warmer, wetter winters (as seen in 2024-2025) boost larval survival, leading to more severe spring damage.
- Regional Hotspots: Urban and suburban lawns are hit hardest due to compacted soils, while rural areas see spikes from nearby wetlands.
- Cycle Predictions: With crane fly swarms peaking in autumn, 2025 could see a surge if summer rains persist, mirroring the “nightmare” outbreaks reported in previous years.
Gardeners are reporting more frequent bald patches and animal digging, signalling a need for proactive measures. Staying ahead of these trends can save your lawn—and your sanity.
Signs of a Leatherjacket Infestation
Spotting leatherjackets early prevents widespread damage. Common indicators include:
- Yellowing or thinning grass in patches.
- Loose turf that lifts easily, revealing grubs in the top 5-10cm of soil.
- Increased bird activity, as species like magpies and rooks forage for the larvae.
- Wilted plants in borders or vegetable plots, as leatherjackets don’t discriminate.
To confirm, dig up a small section of affected turf after rain—if you find more than 25 grubs per square metre, it’s time to act.
Effective Remedies and Treatments for Leatherjackets
Tackling leatherjackets requires a mix of biological, cultural, and preventive strategies, as chemical options are limited in the UK for homeowners.
1. Biological Controls
The go-to remedy is nematodes—microscopic worms that parasitise and kill leatherjackets naturally. Products like Nemasys Leatherjacket Killer are applied in autumn or spring at double strength for active infestations. Apply when soil temperatures are above 10°C for best results, watering thoroughly before and after.
2. Cultural Methods
- Black Plastic Trapping: Soak the lawn overnight, then cover with black polythene. The grubs surface by morning for easy collection and disposal.
- Aeration and Scarification: Punch holes in the soil to improve drainage and remove thatch, disrupting the larvae’s habitat.
- Overseeding: Reseed damaged areas with resilient grass varieties to outcompete future pests.
3. Professional Treatments
For severe cases, consult pros who can use targeted insecticides like Acelepryn (chlorantraniliprole), restricted to licensed applicators. Avoid DIY chemicals, as many are banned for environmental reasons.
Combining these remedies can restore your lawn within weeks, but consistency is crucial.
Prevention Tips for a Leatherjacket-Resistant Lawn
Prevention beats cure. Maintain a healthy, dense turf through regular feeding and aeration to make your lawn less appealing to crane flies. Leatherjackets thrive in compacted, damp soils, so reducing soil compaction is key to improving drainage and deterring infestations. Here at The Robot Mower, our Mammotion LUBA and Segway Navimow robot mowers excel in this—their lightweight design (typically under 20kg) significantly reduces soil compaction compared to traditional mowers, which can weigh 50kg or more and cause up to 20-30% higher compaction levels in studies on turf areas.
Additionally, their frequent, mulching cuts—often daily—promote thicker growth and better nutrient recycling, enhancing overall lawn vitality. Research from the USGA shows robotic mowing increases tiller density by encouraging finer leaves and denser turf, resulting in turf quality ratings up to 8.5 on a 1-9 scale, compared to 5-7 for conventional methods in cool-season grasses. A Virginia Tech study on STIHL iMOW robotic mowers found higher NDVI scores (a measure of plant health) of 0.86 versus 0.74 for traditional mowing, indicating quicker drought recovery and reduced stress—factors that help lawns withstand pest damage like that from leatherjackets. Robotic mowing has also been linked to 30-60% reductions in weed occurrence and lower disease incidence (e.g., 2-3.5% affected areas versus higher in conventional setups), further bolstering lawn resilience.
Shop our range of Mammotion robot mowers or Segway Navimow models for effortless maintenance that supports long-term pest resistance.
Encourage natural predators like birds and beetles by avoiding broad-spectrum pesticides.
Interesting Facts About Leatherjackets
- Leatherjackets can survive underwater for short periods, explaining their love for soggy lawns.
- Adult crane flies don’t eat—they live just days to mate and lay up to 300 eggs each.
- In heavy infestations, birds digging for grubs can cause more damage than the pests themselves!
- These larvae pupate in spring, emerging as flies in summer—completing a cycle that can devastate lawns if unchecked.
FAQ: Leatherjackets in UK Lawns
What causes leatherjackets in my lawn?
Leatherjackets hatch from crane fly eggs laid in damp grass during autumn, thriving in wet, compacted soils.
How do I know if I have a leatherjacket infestation?
Look for yellow patches, loose turf, and birds pecking at your lawn. Digging reveals greyish-brown grubs.
What’s the best way to get rid of leatherjackets UK?
Use nematodes for biological control, or try black plastic trapping. For pros, Acelepryn is effective.
Are leatherjackets harmful to pets or humans?
No, they’re harmless to people and pets but devastating to lawns.
Can robot mowers help with lawn pests?
While not a direct fix, models like the Mammotion LUBA promote healthier, denser turf through regular mowing, aiding overall pest resistance. Studies show they reduce soil compaction, improve NDVI health scores by up to 16%, and cut disease incidence, helping lawns better recover from pests like leatherjackets.
Conclusion
Leatherjackets may be a growing concern in the UK, but with the right knowledge on causes, trends, and remedies, you can protect your lawn and enjoy a vibrant outdoor space. For top-tier tools to keep your grass in peak condition, explore our selection of Mammotion and Segway Navimow robot mowers at www.therobotmower.co.uk. Share this guide with fellow gardeners, and let’s combat these pests together—your lawn (and your backlinks) will thank you! If you have experiences or tips, drop them in the comments below.
