The Problem with Leatherjackets

Crane fly larvae, commonly referred to as grubs, dwell in the upper layers of soil, where they feed on grassroots and plant material. Their presence is most prominent in transition months, and their activity can lead to soft ground and weakened turf condition. Sports fields may become unsafe without proper control.

How to Spot an Infestation

Identifying larvae before serious damage occurs is wise. Watch for signs such as increased bird activity, thinned areas, and irregular surface wear. Cut small patches in the turf to check for larvae beneath. Conducting these checks during cooler months supports better planning.

Understanding Larval Cycles

Leatherjackets can remain active underground during milder winter spells. If they are not managed, the turf’s ability to recover in spring is hindered. Maintenance scheduling based on weather conditions 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 eradicate the pests.

Biological Alternatives

Nematodes, microscopic worms, 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 suppress larval numbers and allow the turf to recover.

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 label instructions. Blending chemical input with cultural and biological steps keeps treatment balanced.

Avoiding Repeat Infestations

To avoid 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 helps predict larval activity levels for the months ahead.

Frequently Asked Questions

• When do leatherjackets feed the most?
  
  They tend to be active 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 direct population check.



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


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



• Why are birds damaging my lawn?
  
  Birds often dig where larvae are present. Their behaviour can be an early indicator of infestation.

Summary

Managing crane fly larvae requires a combination 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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