If you grow cabbages, or any other brassicas, you probably don’t much like white butterflies. The large white (Pieris brassicae) and small white (Pieris rapae) are the so-called cabbage white butterflies. They do lay lots of eggs that hatch into voracious cabbage munching caterpillars.
However, their relative the green-veined white (Pieris napi), which looks very similar to them at first glance, won’t harm your cultivated cabbages and brassicas. Its caterpillars only like to eat the wild plants in the cabbage family.