Leatherjackets
By Cranefly
United Kingdom 
I have tiny (baby?) leatherjackets in my lawn. I had them last year but not this early. The grass is getting worse daily (yellow/borwn patches of dead grass). Earlier this year I have worked really hard in aerating, topsoiling, over seeding and put a treatment on to kill the leatherjackets and it did seem to work, until about a week ago, it is very disheartening to see the lawn just been eaten away. Help please ?!
8 Jul, 2008
Answers
In addition to Kens long term solution which is best as an interim measure and if your garden not too big - water area in evening and lay plastic sheeting over lawn.Remove next morning and give birds a tasty treat , blackbirds love them.
8 Jul, 2008
.Leatherjackets are the larval stage of the crane fly or daddy long legs and they can quickly devastate a lawn. Leatherjackets hatch in August / Sept and immediately start to feed on the grass roots. They will continue to feed through the winter and following spring.
In the summer the leatherjackets pupate and the next generation of daddy long legs emerge in August and start to lay their eggs back in the infected lawns. In August many people report clouds of Daddy Long Legs emerging from lawns in early morning
Apply Nemasys Leatherjacket Killer in Sept / Oct when the leatherjackets are close to the surface and active and the soil temperature is above 10°c / 50°f . Leatherjacket Killer contains a parasitic nematode called Steinernema Feltiae which kills Leatherjackets but is harmless to children, wildlife and pets and also the lawn may be used immediately after application :- Hope this helps you -- Ken
8 Jul, 2008