Below is a quote from a Penn State pubilication I happen to have on white grubs.  I am NOT remotely an expert, but, just happened to bookmark this for a question I recieved one time.  you can read the whole thing with link below.

Publication:   http://extension.psu.edu/field-crop-news/documents/white-grubs-in-pasture.pdf

"Pesticides should not be used as a preventive tactic due to the potential for insecticide resistance, unnecessary costs with no return, and other environmental concerns. There are limited insecticide options for grass pastures, and in general, there are no registered products in PA. In some states, carbaryl (Sevin) 80 WSP, XLR applied as a surface treatment at a rate of 30 gal spray per acre is registered for control of green June beetles in pastures. Treatment is rarely justified. "