In the summer months I get plenty of phone calls and emails from monarch butterfly fanciers, all with a common problem:
“My swan plants are almost stripped bare yet I have so many monarch butterfly caterpillars I really don’t know what to do. Is there anything else I can feed the caterpillars on?”
This problem arises because at times there are too many butterflies laying too many eggs on too few swan plants! It’s as though the butterfly is gambling that at least some of her offspring might somehow get enough food to make it through to the chrysalis stage. If she doesn’t lay eggs on the right food plant they have no chance at all.
So what can you do besides buy more swan plants? Well, there is a partial alternative – pumpkin! I say ‘partial alternative’ because only the older, larger caterpillars can make use of it. While smaller caterpillars can feed on pumpkin flesh, pumpkin doesn’t provide everything they need to properly develop. In contrast, larger caterpillars that have been reared on swan plants are likely to have picked up enough of the chemicals they need to undergo metamorphosis.
It may not work in every case, but it’s worth a try if you don’t want to purchase more swan plants. If you’re still sceptical, check out what the Monarch Butterfly NZ trust has to say on the subject here: http://www.monarch.org.nz/monarch/2005/08/13/pumpkin/