Cottentop,

Congrats on your first corn.

The culprit in the corn case is the corn earworm. The exact same worm will move to tomato plants and eat the fruit. On them it is called the tomato fruit worm. Corn earworms can be difficult to fight, and if you happen to find holes in the side of the husk showing where a worm bored its way through the husk, then that's the European Corn Borer. I have both of them most years, but sometimes none at all.

With the squash, it likely is the squash vine borer, commonly referred to as SVBs around here. I'll link info on them. That's just a guess, though, because it also could be squash bugs or disease. The linked document will address at least squash vine borers and squash bugs, and may go into other things as well.It's been a while since I read it and I don't remember if it goes into other squash family pests and diseases. It can be difficult, but not impossible, to save plants hit by the SVBs if you can catch them on the day it wilts, or even before that, by scouting the base of your plants for FRASS (grub or worm poop). If you find the FRASS, that means the squash vine borer is inside your plant eating away. You can slit the stem, pull it out, press the stem back together and bury it under soil so the soil acts as a sort of band-aid.

Dawn

Here is a link that might be useful: ATTRA: Squash Vine Borers and Squash Bugs