put down a new lawn from sod about a month ago and it all seems to be doing what it should, and most of the sod has rooted nicely to the (all new) topsoil below.

There are though two small areas where the sod has no roots showing at all - lift and see, it is as though the sod had just been layed!? (Same top soil, same watering, etc etc etc). Despite no roots, grass looks good!

Any explanations welcome.

In one location there does seem to be some creepy crawly type scurrying when the sod is lifted....can there be root munchers?

Thanks for any help.