We have had several reports of white grubs on sidewalks and driveways. These are likely the larvae of the green June beetle being driven from the lawn by excess water. To identify for sure, look at a crawling larva closely. Green June beetles are quite large at this time of year (up to 1.5 inches) and the larvae crawl on their back. No other white grub crawls on its back.
Do not be too concerned that these insects are damaging the lawn. The larvae feed primarily on organic matter such as thatch and grass clippings unlike the May beetle which feeds primarily on living grass roots.
The adult beetles usually show up in mid- to late-July and look much like our common May beetle (June Bug) but have a dull, velvety green and tan coloration. The underside is more of an iridescent green. They also differ from the May beetle in that the May beetle has a 3-year life cycle while the green June beetle completes its development in one year. Green June beetles lay their eggs in early August and hatch in about two weeks and start to feed. Only green June beetle larvae are present at this time of year as the adults died some time ago.
Though the larvae rarely cause damage, the adults can be more of a nuisance. Green June Beetle adults feed on ripening fruits such as apricots, nectarines, peaches, plums, prunes, apples, pears, grapes, figs, blackberries, and raspberries. I have seen them most commonly on peaches and blackberries. (Ward Upham)