If you look on the bottom side of the leaves, you will see the yellow oval shaped eggs, usually in a group but you may see an odd one on its own. These can be easily scraped off with your finger and washed down the drain. If you see any baby or adult caterpillars on your plants pick those off and place in a bowl of soapy water or I feed them to our resident robin. If you have too many caterpillars then ‘Dipel’ is what you need. This biological treatment is sprayed all over the plants, don’t forget to spray under the leaves and get into the curled ones. The caterpillars digest this which will poison them and after about 4-5 days they will die. It is harmless to your plants and any other bios you have in working in your garden. The sunlight will naturally breakdown any remaining residues so you may need to re-apply if you still have caterpillars. Sticky traps are also handy and will help catch any other bug hanging around!