Several butterflies laid eggs, and aside from those unfortunate enough to fall victim to their various natural enemies, those ones who manage to hatch and grow need a rich food source to be able to grow up big and strong and have the strength to transform into butterflies.
數隻樺斑蝶產下的卵，除了受到天敵的誘捕外，能夠順利長大的幼蟲也必須有充沛的食物，擁有強健的體魄，才有體力化成蝴蝶。