Did anyone else ever keep these as (temporary) pets growing up? A native to New Zealand (but distributed across many other countries) they are the most commonly recognised non-pest butterfly. As a kid, I would collect them as eggs or day old caterpillars and raise through to butterflies. In New Zealand, eggs are laid on Swanplants between October and May. I would keep them in large empty plastic yoghurt containers (with a see-through plastic lid). One year, I recorded data on each caterpillar including it’s hatch date, time spent in the chrysalis, gender of butterfly etc. These are some interesting facts I found out: Climate greatly affected the survival rate of caterpillars (survival is defined as survival to a butterfly capable of flight). In one year, 100% of my caterpillars born in January and February (height of summer in New Zealand) survived; in March the survival rate was 80%; in April the survival rate was 40%; and in May, the survival rate was 0%. Monarch caterpillars will turn to cannibalism. When a large fifth instar caterpillar ate a small, first instar caterpillar; I gave it the benefit of the doubt and assumed it didn’t see it when eating the leaf. A year later, I forgot to give two medium sized fourth instar caterpillars their morning feed and came back to find a single caterpillar. While I didn’t witness the event, there was no possibility that the second caterpillar had escaped and the inside of the container was covered with (green) blood. In New Zealand, most outdoor caterpillars are killed by Paper wasps. One year, I had over a hundred eggs all hatch outside in a single afternoon. I collected three (I only had three containers) and reared them inside. Not one of the caterpillars left outside survived more than a few days. In April/May, the Paper wasps diet changes to fruit so they lay off the caterpillars. Unfortunately by then, the temperatures are too cold for them to survive. One year a storm knocked over my Swanplant. The stem had fallen on a hanging caterpillar (about to pupate), crushing it in the middle. I rescued the caterpillar and to my surprise, it successfully pupated (a high energy process in which some die from exhaustion) and developed into a healthy butterfly. When the butterfly comes out the chrysalis, it’s wings are wet. They take a few hours to fully dry. It is critical that the wings set in the correct position otherwise they will be deformed and the butterfly cannot fly. The butterfly hangs upside down to let it’s wings unfold. The greatest danger is it will drop and the wings get crumpled. This is most likely to happen in the first few minutes of emerging from the chrysalis and if it is not rescued in 10 minutes, the damage is done. I have had approximately 2% of emerging butterflies drop. In some cases, I’d watched them emerge (and drop) so was able to rescue them immediately.
I never kept Monarch caterpillars, I did raise other caterpillar species as a kid, and sometimes bred adult butterflies (yes - 8 year old birdsandbats was quite an impressive insect keeper). Kind of odd though, as Monarchs are everywhere here.
