What kills ants but doesnt harm the plants?

Boiling hot water, it should kill the ants and shouldn’t harm the plants.

Other people might have better suggestions . . .

xD

Try this stuff called sevin dust. You can get it at a hardware store, lawn and garden place and I think even at like a Walmart. It keeps animals and insects from eating plants, but doesn’t harm the plants or the fruit they bear. I’ve used it before, it works. You just have to remember to sprinkle a little more on each time you water the plants or it rains because it washes off.

What works really well is vinegar with water. I’m not a plant expert… can that harm the plants?

Don’t think ants eat pumpkins! They may be farming scale insects on plants in the area though I don’t think scale normally bother pumpkin plants. Best to watch them for a while and try to work out whether they are up to mischief or not…if not, let them be. White oil spray is a safe treatment for scale. A small container containing Borax with a little sugar mixed in and holes in it can act as a poison bait for ants if necessary.

Put some fresh crushed mint leaves scattered around, they will run outta there faster then you can believe and never to return.