Insecticidal soap will kill any and all adult insects - including the beneficials, but I've been known to "nuke" plants that are seriously infested. A tablespoon of Dr. Bronner's in a quart of water.
Bt (Thuricide) is considered organic caterpillar control. Hand picking is best, although I know how hard it is to see the hornworms when they're small (sometimes even when they're big!).
Have you got female blossoms on your squash? If you don't have a lot of bees you may need to pollinate them by hand. Easy enough with a small kid's paintbrush.
Yep, blanched my beans.
Speed comes from what you put behind you. - Judi Ketteler