The Problem with Leatherjackets

Crane fly larvae, commonly referred to as grubs, live in the upper layers of soil, where they consume grassroots and decaying material. Their presence is most problematic in transition months, and their activity can lead to soft ground and poor turf condition. Public lawns may become difficult to maintain without proper control.

Detecting Larval Activity Quickly

Identifying larvae before serious damage occurs is essential. Watch for signs such as bird pecking, patchy grass, and irregular surface wear. Cut test squares in the turf to check for larvae beneath. Conducting these checks during late winter helps with timely responses.

Understanding Larval Cycles

Leatherjackets can continue feeding underground during milder winter spells. If they are not monitored, the turf’s ability to recover in spring is hindered. Maintenance scheduling based on known behaviour helps reduce pressure on affected areas.

Physical and Mechanical Solutions

Maintenance teams often begin with physical practices. Regular aeration strengthens root growth and improves turf firmness. Raising mowing height during feeding periods can improve resilience, and rolling moist turf may expose larvae, leaving them open to natural predation. These approaches help improve turf quality, even if they do not eradicate the pests.

Biological Pest Control

Nematodes, microscopic beneficial organisms, offer a chemical-free way to address larvae. They are most effective when applied during early autumn, under appropriate moisture and temperature conditions. When timed and applied correctly, they reduce larval numbers and allow the turf to stabilise.

When to Use Approved Chemicals

In some cases—especially on high-demand surfaces—chemical treatment may be necessary. Authorised turf protection products may be applied, but only according to current regulations. Blending chemical input with cultural and biological steps prevents overuse.

Avoiding Repeat Infestations

To minimise outbreaks in future seasons, aim to optimise drainage, encourage strong rooting, and maintain balanced nutrient levels. Monitoring turf after crane fly emergence in late summer indicates larval activity levels for the months ahead.

Frequently Asked Questions

• When do leatherjackets feed the most?
  
  They tend to be present in greater numbers during mild periods in autumn and spring.



• How can I be sure I have a problem?
  
  Cut out a small patch of turf and count the number of larvae beneath. This provides a practical population check.



• Can nematodes survive in cold soil?
  
  No. They require specific temperatures and soil moisture to be effective.



• Does mowing height matter?
  
  Yes. Leaving grass slightly longer during larval feeding helps reduce plant stress.



• Why are birds damaging my lawn?
  
  Birds often peck where larvae are present. Their behaviour can be an unintended clue of infestation.

Summary

Managing crane fly larvae involves a blend of early detection, well-timed treatment, and varied management strategies. By combining physical methods, biological control, and limited chemical use, turf conditions can be protected throughout the year.

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