I've raised monarch butterflies for all my life. The butterflies come and lay eggs on my Milkweed I have in pots around my backyard. I place cages around the milkweed when there is caterpillars on the plant. The cage are there to prevent wasp from eating them and without the cage none of the caterpillars would survive. The monarch butterfly is a threaten species in North America. If others in areas where Monarchs live could plant Milkweed & try to raise the butterflies it would well worth your time.