Q.Squash Grub
My squash plants are falling over limp, so I’ve had to pull some of them up. On one such plant.the root snapped and I saw a white (grayish) grub-like critter with a black snout. So when I pulled other plants, I examined the roots and found they were all being eaten from the inside out. What are they, and what’s the cause and remedy?

Certified GKH Gardening Expert
That is a description of a vine borer, though you normally find them in the stems rather than the roots. This article will help you with dealing with them in the future:
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-pests-identifying-and-preventing-squash-vine-borer.htm