Please post images so that we know what you mean by "grub worm."

"Grub worms" most often are the larva of the scarab beetle, a "C" shaped ugly thing that feeds on organic matter in the soil. These larva hatched from eggs layed about last August by the various scarab beetles, June bugs and Japanese Beetles are two, we have around us and are now getting ready to change into the adults that will fly around looking for a mate so more eggs can be layed to produce a crop of beetles next year.
The best thing to do with them now is to feed any you find to the birds. Spreading poisons to control them now is not very effective. To keep the population down next year spread controls, Bacillus popilleae (Milky Spore Disease), parasitic nematodes, etc. in August to catch these as they hatch and are much more easily controlled.

Here is a link that might be useful: Grubs