Our Pest Control Expert, Julian Ives, has spent many years advising commercial growers and gardeners on the subject of safe and efficient natural pest control treatments.

Here he shares his experience on the problems Leatherjackets can cause in the garden and how to get the best results from the Leatherjacket Killer nematodes...

Using Leatherjacket Killer Nematodes
Apply when the young leatherjackets are active in the soil, this is from late August-October. It is possible to treat Leatherjackets in the spring but it is not as effective, due to the soil temperature being low and the overwintering leatherjacket larvae being larger. For spring applications the soil temperature must be over 10.c and a second late summer application will also be needed. Leatherjacket Killer can be applied with watering can or a hose end feeder nematode applicator. The soil must be moist prior to application. After application water the treated grass area again to ensure that the nematodes reach the roots of the grass where the leatherjackets will be present. Keep the lawn moist for two weeks after application. The leatherjacket killer nematodes seek out the leatherjacket larvae and enter the pest. They release bacteria inside the leatherjacket that kills it. The nematodes then reproduce inside the leatherjacket and are released into the surrounding area to search for more leatherjackets.

Appearance and Lifecycle
Leatherjackets are the larvae of crane flies, more commonly known as Daddy-long-legs. The larvae are grey to brown in colour and about 2.5-4cm long. The larvae are headless with no legs. There are several species but the most common one is seen as adults flying from late August to October. Mating and egg laying occurs within 24 hours of the adults emerging from pupation. The eggs quickly develop into Leatherjacket larvae. The larvae overwinter in the soil until the following spring and then start feeding again when the soil temperature rises.

Symptoms and Damage
Leatherjackets are normally found in lawns, although sometimes they will occur in vegetable patches and flower beds. One of the first signs of leatherjacket activity is grass growth slowing and yellow patches appearing. This is where the leatherjackets are feeding on the roots. In severe cases the grass can easily be pulled up. Clouds of daddy-long-legs flying around lawns should be a warning call that leatherjacket larvae will follow. The secondary damage resulting from leatherjackets can be even worse. This is caused by birds and animals ripping up lawns looking for leatherjackets to eat.

Natural Choice Treatments
The only non-chemical treatment for treating leatherjackets is the use of nematodes, other than digging up the turf and removing the leatherjackets underneath. Black polythene can be placed over small areas of lawn and left overnight, the leatherjackets then move up into the grass for removal This is however not a very practical way of treating large areas of lawn infested with leatherjackets.