July 10th: At least two of the eggs hatched (I can’t find the others). That was about four days as an egg, since it was laid on July 6th. No time to waste!
July 20th: One caterpillar is dead, but others have molted from their black and white form into gleaming green and black beauties. So far, I’ve found four caterpillars of which one is dead, one missing and two doing well. This is looking more and more like reality TV: Who Will Become a Butterfly? In the night, a contestant missing. His bush mate found dead, hanging from a branch by two prolegs. Meanwhile, two others are growing fast, neck and neck* in a race to be first to pupate! (* do caterpillars have necks?)
July 22nd: Where are the caterpillars? Are they hiding, moved to another part of the plant? Most caterpillars can’t other plants than their host. Anise Swallowtails need things related to carrots (fennel, parsley…). Monarchs only eat milkweed, etc.
July 28: No sign of the caterpillars. Looks like they’re gone. So, one caterpillar found dead; the others missing as soon as they started to get bigger. Biologists have a word for this kind of thing: “stochastic factors”. This basically boils down to bad luck. Too bad the caterpillars sat where birds would see them and gobble them up. Too bad there was a bacteria in the area that kills caterpillars. Too bad that a predatory wasp was passing by… That’s why butterflies lay a lot of eggs: to ensure that at least a few reach adulthood, breed and start the cycle anew.
There is a lesson here: even if your landscape is pesticide free, full of viable habitat (in this case, food plants), and as insect-friendly as you can make it, this does not mean that it will work to regenerate local populations. The very things that make it caterpillar friendly also make it a dangerous place for them, since their predators are alive, unpoisoned and free to devour them. It’s also bird-friendly, and birds are happy to devour many types of caterpillar (although not others, since they may be poisonous).
Another lesson is that there has to be a local population of the butterfly you’re trying to support, or at least an individual that strays into your garden long enough to lay some eggs. We have a flourishing California Dutchman’s Pipe vine, yet have never seen a caterpillar nor a Pipevine Swallowtail butterfly anywhere near the vine. We’re also trying some milkweeds in the hope of attracting a monarch or two, but so far these insects have not visited. Ditto for White-Lined Sphinx moths and their food plants. Although this isn’t all bad – we haven’t had hornworms on our tomatoes yet, either.