Are you able to share photos? You can attach the files to your reply here, or paste the images directly into the body of your reply. What is the plant they are eating? While some caterpillars are distinctive-looking enough to be identified by themselves, context is important and what they are eating can narrow-down the identification considerably. If you don't know the name of the plant being eaten, including a photo of that can also help us to ID it. Once we know what the insect is we can share recommendations for treating the plant. Fortunately, very few caterpillars, even those causing drastic defoliation, warrant intervention because the plant will recover on its own and the leaf loss is only temporary.

Miri