[caperpat]

I have a border of creeping phlox and I noticed it looks like it's dying. When I checked, I could pick it up, like the roots weren't attached to the soil. Then I saw a bunch of grey,grub like things in the soil. I sprayed with Raid, put new soil there, and it seemed to be OK. Now it's the same way again. Can you tell me what these creatures are and how to get rid of them?
Thanks so much
Pat Ontario Canada