The Problem with Leatherjackets

Crane fly larvae, commonly referred to as grubs, dwell in the upper layers of soil, where they consume grassroots and plant material. Their presence is most noticeable in moderate seasons, and their activity can lead to soft ground and poor turf condition. Managed landscapes may become unsafe without proper control.

Recognising Early Signs

Identifying larvae before serious damage occurs is wise. Watch for signs such as increased bird activity, patchy grass, and irregular surface wear. Cut test squares in the turf to detect larvae beneath. Conducting these checks during late winter supports better planning.

Seasonal Risks to Grass Condition

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

Cultural Turf Management

Groundskeepers often begin with physical practices. Regular aeration strengthens root growth and improves turf firmness. Raising mowing height during feeding periods can reduce stress, and rolling moist turf may disrupt larvae, leaving them open to natural predation. These approaches help bolster turf quality, even if they do not fully eliminate the pests.

Biological Alternatives

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

Supplementing with Registered Products

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

Reducing Future Risk

To minimise outbreaks in future seasons, aim to improve drainage, support 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 feeding in greater numbers during cool and moist periods in autumn and spring.



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



• Can nematodes survive in cold soil?
  
  No. They require moderate 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 early indicator of infestation.

Final Advice

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

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