If you saw one, it is very likely that you already have eggs. They look like the picture below, and will usually be on the stem close to the ground. Sometimes they are on the leaves or higher up. Scrape them off if you find them. If you have an infestation, there will be a small hole somewhere on the stem with "frass" - basically insect poop - just outside of the hole.

Thank you I’ll look out for those closely. My plant has been putting out roots at every single leaf into the ground is this alone good enough to keep it living? And I’m not gonna eat these so do you think BT would work if injected into the stems of the plants if there’s already caterpillars eating the insides? Thanks

Yes the new roots will make a big difference and will be very helpful. They might be enough all on their own and they might not - it depends on where the roots are and where the caterpillars are. And yes injected BT works, if and only if you inject it into the right spot so that it gets to the caterpillars. If you inject it where they've already been past and eaten their way through the vine, nothing happens. BT is considered organic and there is no damage done from eating pumpkins from plants previously injected, however it is of course your choice to make. Some gardeners will also split the vines looking for the caterpillars and then wrap the vines to heal over after the caterpillars are gone, but that of course is also risky.