no guesses. My philosophy on bugs in the garden is simple. They are all there to eat plants or eat things that eat plants. Learn to ID those that eat other bugs (or pollinate) and squish the rest.

There are a zillion bugs in the world, but in a garden the majority of bugs are there to eat something or to breed/lay eggs in which case the hatchlings will eat the plants or other bugs.

*ANY* caterpillar in the garden is there to eat plants. If this wasn't the case the adult bug wouldn't have laid eggs there.

Justaguy said, "Learn to ID those that eat other bugs (or pollinate) and squish the rest."

I agree. That's why I'm trying to find out what kind of bugs these are.

Then you said, "*ANY* caterpillar in the garden is there to eat plants."

Yes, but if there are predatory thingees on this caterpillar, I'm figuring I'd be better off letting those thingees do their job and then multiply so their offspring can continue find more caterpillars - I'm guessing they can find them a lot better than I can, and with no work on my part other than letting them be.

posting a picture goes a long way toward identification.

If a caterpillar is infected with parasites then yes, leave it be, but many caterpillars have hairy 'bumps' that are normal.

Caterpillars turn into butterflies...can you leave some caterpillars? Butterflies populations are suffering due to loss of habitat, and they do play a role in the biology of gardens.

There are some good identification sites on the internet, ralgam.

I think we need some pictures of your critters before they can be properly identified. You've mentioned two insects that 'look like' squash bugs, but really don't. ;-) And a caterpillar that might not even be a caterpillar. (There are other larvae that are caterpiller-ish.)