As spring unfolds and temperatures rise, homeowners across the country are discovering that their once luscious lawns are being torn to pieces.
The culprit of the damage? The lesser-known leatherjacket.
Leatherjackets are small grubs that are the larvae of crane flies, or daddy long legs, and are infesting lawns, wreaking havoc and causing concern among gardeners about the fate of their much-loved turf.
Unfortunately, it would appear that infestations this year are particularly rife. This is because leatherjackets thrive in moist and mild environments, so last year’s damp, warm autumn followed by this year’s even wetter spring has created the perfect conditions for these grubs to thrive.
Although harmless to humans and wildlife, these voracious pests can quickly decimate plant roots, seedlings, and grass, and can quickly transform green and gorgeous grass into sparse, brown mud patches. What’s more, the presence of these grubs also encourages birds and mammals to cause further damage as they dig up the garden in search of larvae to feast on, leaving behind rounded, deep holes.
Since 2016, all effective pesticides to treat leatherjacket infestations, such as chlorpyrifos, have been banned in the UK. Thankfully, one of the most simple, effective, and biological methods to tackle them and restore lawns to their former glory is to apply nematodes.
Nematodes are naturally occurring, microscopic worms that target and kill common garden pests, like leatherjackets, without causing harm or disruption to other wildlife, pets, or people. Not only are nematodes effective at controlling and destroying pests but applying them to the garden is also very simple. In fact, it’s as easy as watering your garden!
Matthew Martin, from Nemasys, the UK’s largest producer of nematodes, shares his advice on spotting a leatherjacket infestation and how to banish them quickly and effectively for good.
“The easiest way to tell if you have a leatherjacket infestation is to find a grub - they’re not too hard to spot,” he said. “They have long, elongated tubular bodies and can grow up to 30mms. They have no obvious head or legs and can be brown or black in colour. To encourage them out of the lawn, you can saturate the grass and cover with black sacks or tarpaulin overnight.
“In the morning, the grubs will have risen to the surface and will be easy to see. They can be discarded by picking them off by hand or left exposed for the birds to consume. With severe infestations, it is possible to lift the first layer of soil with a shovel or trowel and spot the critters wriggling around just below the surface.”
Nemasys Biological Leatherjacket Killer specifically targets leatherjackets by attacking the larvae, entering through natural openings or pores in the grub’s body, and then releasing bacterium from inside, which infects and kills the pest. Nematodes should be applied directly to the lawn when the soil temperature is consistently above ten degrees, meaning now is an ideal time to treat your grass.
The nematodes arrive as dried granules that are then mixed with water in a watering can or suitable sprayer, and simply watered onto the lawn. It’s best to apply them first thing in the morning or during the evening to avoid weakening the nematodes with harsh direct sunlight.
The lawn should be well-watered after the application to wash the nematodes into the soil, and the area should be kept wet for up to two weeks afterwards. For consistent and long-lasting protection, it’s best to repeat the application after two to four weeks to keep your garden grub-free and thriving.
