Squash Problems

Having problems with my Spaghetti squash. I have 4 plants here, and one of them took a bad turn a couple of days ago. I took this picture this morning showing all 4 squash plants. The other three looked healthy this morning. (Click for larger pictures).


This evening another squash plant (the furthest one away in the above picture) looked all wilted, but most leaves still look good. I have examined both plants for Squash Borer Worms but found no evidence. I gave the garden a drink of water because the dirt was dry, but the rest of the garden including 2 other Spaghetti Squash and other yellow squash plants all look good.