Leatherjackets and How They Damage Lawns

by Cameron Shimoda · Published September 1, 2021 · Updated November 8, 2023

Even though the adult European crane fly doesn’t bite or sting, their strong resemblance to mosquitoes – and big ones, at that – makes them an unwelcome guest in the garden and on the patio. They generally come around in late August and mid-September. Within 24 hours of emerging, they mate and the females will lay their eggs in the grass. Then, an even worse nuisance will come out: leatherjackets.

Leatherjackets: The Lawn Menace

It’s the earlier stage of the crane fly life cycle that you need to be aware of. This is when they can cause a lot of damage to your lawn. The eggs will hatch and at the larval stage, they’re called leatherjackets. Unfortunately, it’s kind of a fitting name because they’re pretty tough little bugs.

 

For a comprehensive article from Cornell University all about Crane Flies, click here!

 

Generally, they stay under ground and gobble at your grass’ roots in autumn and again in spring as the weather warms up. But on warm damp nights, they’ll come up and eat away at blades of grass too. This goes on until mid-May, and then they go into a non-feeding stage just below the soil for the summer. That’s when the whole cycle starts again.

What Does A Leatherjacket Problem Look Like?

The big problem is, as they’re eating your grass’ roots, they’re killing your grass. Not only that, but birds will dig at your lawn to try and get at them for a bit of ‘surf and turf.’ If it’s a small population of leatherjackets in your lawn, then your grass will fare reasonably well, especially if you’re taking steps to ensure a healthy root system overall (you can read more about that here). But the problems come when the population gets to be too dense, around 25 to 30 larvae per square foot. That’s when you’ll see damage on your lawn, particularly in the spring. 

How Can I Get Rid of Leatherjackets?

So, what can you do? Fortunately for you (and unfortunately for them) leatherjackets dehydrate quickly. When you see the adults laying eggs, stop watering your lawn. Let the top few centimetres dry out, and the eggs will collapse.

 

You can also use beneficial nematodes, but keep in mind they must be applied to your lawn just after the eggs have hatched and the leatherjackets are still small, generally in September and early October. Be sure to read and follow the directions on the packaging! 

 

If, however, you find that the damage is too extensive, you might consider replacing the turf altogether. We recommend you visit www.OrderSodNow.com. Not only is it incredibly easy to order your new rolls of sod, but our easy online calculator will help you determine exactly how many rolls you need based on the space you’re trying to cover – we do the math for you! 

 

We have a really helpful post here that will walk you through how to lay new sod. Just remember that if you’re combating leatherjackets by replacing your turf, it’s really important to remove the top few inches of your existing soil to make sure you’re not laying new sod on an old problem.