Doctorbob, who is one of our members, advised me to put a tarpaulin on the lawn in November, over night. In the morning, take it off and sweep up the leatherjackets.

Goor luck - I hope it works for you. I'm going to try it!

If they're still there now as maturing grubs, they'll probably get killed off by the cold soon. They normally emerge as adults about now (or a little earlier). It's the eggs that the recently emerged adults have laid that will be the problem, as the newly hatched grubs will start to feed soon, and in mild spells throughout winter. So it's particularly next spring year that you'll be looking to cover. Provado Law Grub killer apparently does the job. It's recently introduced. Phil J

It's best to use the tarpaulin when the grubs are small, as they get larger crows etc. will come in and start eating them and they can tear a lawn to pieces, within a week. The Provado Lawn Grub killer retails at about £14 to cover 100 square metres, you can only put one application down each year, it is yet to be proved what damage it will cause to wildlife and domestic pets.

There's a nematode solution for these, best used August - end of October, which can be watered on, Nemesys for leatherjackets. No harm to the environment with this.

As Bamboo says, the Nematode solution is the best, safest and most garden-friendly option - cut and paste link below for more info:

http://www.ecocharlie.co.uk/garden-care/pest-and-disease-control/nemasys-leatherjacket-killer.html

My problem with nematodes is that we have so much lawn - it simply wouldn't be feasible.