Mystery brown lawn patches

My lawn has developed a number of brown patches, but to date I've seen very few crane flies or leather jackets about.  I enclose a photo to give you an idea of what the lawn looks like.  Should I treat it with nemasys in September or is it likely to be something else?
 
Regards
 
Cuan Coulter  

It is a short but succinct answer - I think it is leatherjacket causing the brown patches on your lawn.  The application of Nemasys Leatherjacket Killer is undoubtedly the best solution.  

Thank you for your enquiry and all the best in solving this problem.

Julian