Things were bad last year in terms of the butterfly population, but seem a bit better this year. This cheered me up quite a bit, seeing that nature keeps fighting inspite of all the herbicides and neonicotinoids. Our insekt population is way, way down. Decades ago, after a short drive, your windshield would be full of dead insects. Today, I believe you could drive from here to Hamburg on a warm summer evening and have close to none. As a side note, this is also why I feed the birds year-round – they need help.
Anyhow, a few weeks ago, I noticed a swallowtail butterfly in the yard, sauntering lazily from plant to plant, as they tend to do. A few days later I checked the dill that we keep planted precisely for this purpose, and discovered two freshly deposited butterfly eggs.
I removed the dill to which they were attached and gently bedded them in a bowl with a lid. I checked them twice daily, as if they hatch and have nothing to eat, things will get dicey, and they hatched after only about four to five days. Now, about 12 days later, one has attached itself to the side of the “butterfly box” and is now a pupa, while the other is still merrily eating fresh dill and growing just a bit more.
Why did I not leave them to grow and prosper in the wild? Because of parasitoid wasps, which like to inject their eggs into these caterpillars. The egg then hatches inside the caterpillar, and the resulting wasp larva feeds on the inside of the caterpillar, eventually killing it. Some types of wasp larvae actually make it to the pupa stage. I collected about 52 caterpillars (swallowtail) in the wild years ago, cared for them until they transitioned to pupa. The following spring, more than half of the pupa hatched wasps instead of butterflies – it was devastating to me.