I have a serious grub issue. My lawn was bad so I ripped up my whole lawn completely to start over and I was wondering if the grubs will die now that there is no grass to eat and how long will it take.
Grubs are the larval forms of several beetle species, with different life cycles. A month or more without food should be enough to kill the grubs that hatch, but its also possible that eggs could go into a dormancy if conditions aren't right (like having no grass roots to eat,) just to hatch out when the grass is back. Also, even if you kill the grubs that are present, in a few months the parent beetles will lay more eggs. Here's an article on different methods of grub control:https://www.gardeningknowhow.com/plant-problems/pests/lawn-grubs-how-to-get-rid-of-grub-worms.htm
And another article with some more info on beetle and grub control: http://ento.psu.edu/extension/factsheets/white-grubs-lawns