How can i control them? I hate to use pesticides as I believe that the butterfly population is as threatened as bee population. Or how can i prevent the butterflies from laying their eggs on my grapefruit, lemon and lime trees (that i grow in pots). When i see the Monarchs flying around my yard, i know it's egg laying time. Last year, you could hear them 'crunching' on the leaves and they just destroyed the foliage - and hence no fruit.
Or . ..  should i be content to grow the plants to feed the larvae and help the butterfly population? thanks.