The Problem with Leatherjackets

Crane fly larvae, commonly referred to as grubs, live in the upper layers of soil, where they damage grassroots and plant material. Their presence is most problematic in moderate seasons, and their activity can lead to spongy ground and deteriorating turf condition. Public lawns may become unsafe without proper control.

How to Spot an Infestation

Identifying larvae before serious damage occurs is wise. Watch for signs such as bird pecking, thinned areas, and irregular surface wear. Cut small patches in the turf to detect larvae beneath. Conducting these checks during early spring helps with timely responses.

How the Seasons Influence Turf Health

Leatherjackets can continue feeding underground during milder winter spells. If they are not kept in check, the turf’s ability to recover in spring is delayed. 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 reduce stress, and rolling moist turf may disrupt larvae, leaving them open to natural predation. These methods help improve turf quality, even if they do not fully eliminate the pests.

Biological Pest Control

Nematodes, microscopic beneficial organisms, offer a natural 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 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 label instructions. Blending chemical input with cultural and biological steps preserves soil health.

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 indicates 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 section of turf and count the number of larvae beneath. This provides a practical 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 unintended clue of infestation.

Final Advice

Managing crane fly larvae requires 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.

Need professional help? Visit ALS Contract Services for more information.