Are they in containers or in-ground?

The leaves are so large that they transpire a LOT of water during the day, so you may have to increase the water to them. I've found the "semi-wilting" in container-grown squash quite often, and just this morning moved the one squash that looks healthy and vigorous that I started early out to the garden in its container.

Since the container has a good-sized hole in the bottom, I'm going to dig a 3-4 inch deep hole the diameter of the container to set the container in, and then surround it with earth and mulch so it can draw water from the garden soil. That way, it can reap the advantages of my drip-hose irrigation system.

I think all my large leaves wilted, but theres plenty of young new leaves growin in its place, circle of life? All mine are containers.