I usually pick them off by hand, but you can buy insecticides that are safe for your crops if you prefer to.

I couldnt tell you which plants but there is system i believe it gets good results,which is companion planting.You mix your veg plot up with flowers that divert pests and plants which confuse pests with aromatic scents.,all you can do is pick them off for now and spray with crop friendly spray as Seaburn girl advises.I would research com. planting for future though.