Do the squash beetles attack other plants, or just the squashes? I ask this because I rotate where I put different crops each year and so won’t be putting my squashes in the same area they were in last year.
They bore into the vines and kill ‘em, or at best stunt them so they can’t bear. They make little perfectly round holes in the ground right next to the vine, and get on squash (even summer squash and zucc), and sometimes pumpkins, not on watermelon (which is not a cucurbit) that I’ve ever noticed. Nothing else I know of.
Squash vine borers are larva laid by a moth. The moth flies by, lays her eggs, they hatch out and bore into the squash. They run in cycles—worse around a full moon and about the middle of June and then Aug. if you can get your plants up big enough so that the stalks are tougher, thevb’s will have a harder time. Also, as soon as your seeds emerge from the soil or you plant your plants, dust the stems with rotenone or sevin. i prefer rotenone because it’s easier on bees.