Typically monarch butterflies begin appearing in Maryland in late May. The summer monarchs live 2-5 weeks; laying eggs on milkweed plants and sipping nectar. Laying a single egg per plant, females can lay between 100 and 300 eggs. The growing caterpillar eats only plants in the milkweed family (Asclepias sp.). After pupation, during which the larva undergoes metamorphosis to become an adult, the monarch lives on nectar from a wide array of nectar flowers.