The spring of 2020 has seen a huge rise in the number of leatherjackets infecting lawns. Two mild winters and a damp summer and an eradication of any controls back in 2015 has brought an explosion in numbers of the insects. If your lawn looks to be suffering, have a dig around, you may find the culprit. So what do you do if you find leatherjackets in your lawn?
If your lawn has suffered this winter, remember these steps to bring your lawn back for the summer.
Reducing the numbers of the grubs in the lawn must be the first step. If you try to repair the lawn with a leatherjacket infestation still in the soil, they will just eat the new grass! You need to make sure the majority have gone (or pupated) before attempting any repairs. This will save you money and time in the long run, and bring you a much better lawn in the end.
But how do you reduce the numbers?
I advise a three-pronged attack to battling these wriggly beasts.
- Water, cover and collect: Give one area of damaged lawn a good watering. Then place something over that area which completely blocks out the light. Old tiles or patio slabs are good. Thick plastic weighted down also works. Leave it at least overnight and then when you lift it in the morning they should all be sitting on the soil surface. Simply collect them up and feed them to the birds. Doing this regularly will quickly reduce the numbers in the soil.
- Garlic Spray: A bitter-tasting spray on the grass will discourage the grubs from eating the grass an they will wriggle away. Hopefully to be caught by birds or swept up off your patio. I have a professional organic garlic spray which I can apply to customers lawns, or you could try to make some yourself by soaking crushed cloves in boiling water overnight.
- Nematodes: These are microscopic nematode worms which are parasites to the grubs. When watered into the lawn they are supposed to protect from infection and reduce numbers. However, do not expect miracles from this treatment and the application instructions must be followed to the letter for them to have any chance of working. Don’t rely on nematode control alone, but it is worth trying.
Repair the lawn
Repairing the lawn can be done once the numbers of grubs are sufficiently reduced. If they are still in the soil when you try to repair it they may just eat your new grass! I recommend re-seeding rather than turfing the damaged areas. There will be less chance of re-infection with fresh seed. Since there are no pesticide controls available to turf farmers there is a chance your new turf may arrive with chafer grubs or leatherjackets in your lawn from new. That would be a terrible waste of money.
For small areas, follow my picture guide to patch repair.
- Loosen and prepare the top layer of soil. Prepare it to a fine tilthe and remove any debris for best chance of success.
- Sow new, fresh grass seed. 75 grams per square meter for bare areas.
- Rake in and level. This is to get good soil contact with the seed to aid germination.
- Water in. This is to start off the seed germination process.
- Protect and keep moist. Birds may try to eat the seed and it does not want to be stepped on whilst it is growing. Also remember to keep it moist, especially on hot spring days.
Preventing reinfection is the final step to keeping your lawn looking great for years to come. Leatherjackets are an annual pest. Once they have turned into crane flies and flown there will be no grubs left in the soil. However, how do you prevent them from laying eggs in your soil again? Here are the steps you can take to help your lawn be resistant in future years.
- Promote deeper roots and healthier grass. Healthier grass is in a much better position to resist being eaten by grubs. A well aerated, healthy lawn is much less likely to suffer damaged and will recover more quickly. Crane Fly’s also seem to prefer grass with high levels of thatch, so scarify, if needed.
- Increase cutting frequency in late summer. When adults are flying and laying eggs, running a mower over the lawn more frequently will help to disrupt them and suck up any eggs in the soil surface.
- Autumn nematodes. Applying a preventative nematode treatment in the autumn will help the soil to build up a resistance. However, don’t rely on this alone. An attack can happen to any lawn.
- Attract birds all year round. Birds are fantastic predators to crane flies and leatherjackets. Encouraging them into your garden all year round and their numbers will reduce. Plant shrubs and plants for them to hide in and bird feeders for winter snacks.
- Be vigilant all winter. Keeping an eye on your lawn through the dark winter months is important. A professional winter treatment will spot problems before they turn serious. You can then take steps to control their numbers.
No more Leatherjackets in your lawn
So, if your lawn has been devastated this winter, don’t despair. Remember R.R.P … Reduce, Repair, Prevent. Follow these steps and you’ll have a great lawn this summer.
For a more detailed look at the crane fly and the leatherjacket larvae, and a look at my complete guide to leatherjackets. This will help you to understand your enemy!
Further reading on Leatherjackets in your lawn
- Royal Horticultural Society – Leatherjackets
- Premier Lawns on Leatherjackets
- Pitchcare – Crane Fly