What Are Leatherjackets?
Leatherjackets are Crane Fly (Daddy Long Legs) larvae. They look like greyish-brown grubs and live in your soil where they eat the roots and base of plants, which can cause quite a lot of damage to your lawn if you have a lot of them.
Having some leatherjackets is natural and does not require you to go on a leatherjacket killing spree but if they start to destroy your lawn then you’ll need to do something about it.
About 300 leatherjacket eggs are laid in the grass at a time in late summer and take about two to three weeks to hatch if it is not too dry, and once they do, they immediately start to feed on your plants.
However, when they are small, they are quite weak and cannot do that much damage but when Spring rolls around they can reach up to 10mm and eat much more before burying deeper into the soil in the Summer to form a pupa. Then, when the crane fly is ready, it will emerge in late Summer to start to cycle again.
How To Know If You Have A Leatherjacket Infestation
Leatherjackets have to jump a few hurdles to make sure that they survive through the months until they hatch into crane flies. If the weather is too dry, then they will perish and if there are animals grazing like cows or chickens, they will also be snatched up quickly.
Having said this, since a large number of leatherjacket eggs are laid at the same time, there is still a good chance that you will get more than your lawn can handle.
There are ways to tell that you have a leatherjacket infestation, and most of them are easy to spot. If you find you are starting to see patches of dead, dry grass in your lawn then it might be due to leather jackets as they eat grass roots.
However, patches of dead grass can be caused by several other problems but to see if it is due to leatherjackets, you can remove a small section of grass and if you see lots of leatherjackets then you have caught the culprit red-handed.
Another way to see if you have a leatherjacket problem is if you see lots of disturbance in your lawn such as birds pecking and animals digging and damaging your soil then it is probably because they are feasting on the abundance of leatherjackets.
How To Get Rid Of Leatherjackets
Now that you are sure you have a leatherjacket infestation, it is time to get rid of them and bring your lawn back from the dead. Initially, your next step depends on how bad your infestation is. You can either repair the lawn or replace it if there is not much leftover to salvage. If your lawn is quite small then it is more cost-effective to replace it than it would be to repair it.
If this is the case and you have decided to replace your lawn, the first thing you need to do is kill the whole lawn by using a weed killer that contains glyphosate. Leave the weedkiller on the lawn for a couple of weeks so that it has a chance to work its way down into the roots.
By doing this you will kill all the weeds and seeds that are in the lawn and soil which prevents the weeds from growing through the new turf. As well as this, the leatherjackets will be left with no food supply as they feed mostly on grass.
Once the weedkiller has gotten down into the roots and killed the whole lawn, it is time to remove the dead turf. This is the part where the local bird population will help you out.
By using a spade, dig up parts of the soil and turn them over so that the leatherjackets are exposed. Do this every day for about two weeks and the birds will flock in no time to pick them off and drastically reduce the infestation.
If you do not live in an area with a lot of birds such as a city then you can sprinkle nematodes into the exposed soil which are little creatures that release fatal bacteria into the body of other insects, such as leatherjackets. Finally, once you feel that the majority of leatherjackets are gone, you can prepare the ground for new turf.
Instead of replacing your whole lawn, you can choose to repair it instead which is a better option for those with bigger lawns or less area of damage. You want to create a good base for sowing grass seed and to do this, you should mow your lawn and then scarify it which removes the excess dead grass and benefits the overall health of the lawn.
Next, you can sprinkle nematodes into the soil which will kill the leatherjackets and they will continue to reproduce which will help control your leatherjacket population later down the line. Once you have applied the nematodes, you must make sure the lawn stays moist for at least two weeks and if it is dry, you can water the lawn every couple of days.
After this, your lawn might look a bit rough with patches of grass missing and scruffy grass so you should use a good quality grass seed to bring it back to life.
To ensure that the grass seed germinates and grows quickly, you can apply a fertilizer that will give the grass a good head start. If it is not raining regularly, water the lawn, and after a few weeks it should be good as new.
How To Prevent Leatherjacket Infestations
Bouncing back from a leatherjacket infestation takes time, money, and hard work so you probably want to make sure it does not happen again.
By keeping on top of your lawn care you have less chance of getting another infestation. You can do this by cutting the grass regularly, scarifying, and fertilizing which keeps it strong and healthy which makes it harder for crane flies to burrow into the soil and lay their eggs.
As well as this, nematodes are your best friend when you have a lawn and can be used as a preventative in the Spring and Autumn when leatherjackets tend to be most active.
An easier way to kill leatherjackets?
You might be left feeling a bit deflated with all the work that needs to be done, and maybe wondering if there is anything easier. Over the last year, I have been using a product called Turfsolv on customer lawns (available here). It’s an organic non toxic product and does appear to have positive results.
I’ve found the best way to apply it is once per month right through the year, as it helps with both plant health and controlling leatherjacket numbers and also chafer grub numbers.
