If the caterpillars are visible, hand pick and squish. Keep repeating until no more appear - eggs may hatch and so they could come in waves.

Why cut your plant when you can wash it? Here's a link to washing houseplants that might be useful.

FataMorgana

My mints grow strong underground runners. That is one reason their prowth must be restricted with some kind of a barrier if you dont want them to invade all your garden.
If caterpillars eat your mint, cut them back hard, they will grow back nicelly, plus the caterpillars that hatch from the eggs left behind will have a hard time growing with less food.

Thanks for the tips!
I think I will severely cut it back, because I'm squeamish and the thought of having to touch those caterpillars... ick!!!

I'm happy to hear the mint will grow back strong afterwards. It's in a big pot on my balcony, I might switch it to a bigger one soon - better to wait for the Fall, right?

If it's potted I woudn't be very concerned. After all you can take it inside near a window where it gets sunlight.