[shawsbelfast]

Help I am an amature!!!!  I have had a professional tell me I have an infestation of Leatherbacks in my lawn.  He has said that he can spray with Dursban and then reseed the effected areas.  Can anyone advise if there is a right or wrong time of year to do this procedure as I am unsure if he is spraying a lawn where larvae have already left.

[JayG]

He probably meant leather jackets, the larvae of the crane fly.

Dursban is quite a "nasty" insecticide which is actually banned for home use in the US, and I don't know whether your professional is or should be licensed to use it here, so you might want to consider using one of the methods suggested by the RHS.