Caterpillars hatching and feeding. Macrophotography footage of cabbage white caterpillars (Pieris brassicae), in various stages of hatching and eating their egg cases prior to eating the leaf. The leaf has been transilluminated. Cabbage white butterflies lay their eggs on a number of plants. The eggs hatch over a period of 2-7 hours, and the caterpillars then cause extensive damage by feeding on the host plant's leaves.