Well, our experience raising Monarch butterfly caterpillars came to an end about two weeks ago. The kids had a lot of fun watching the caterpillars grow, molt into their chrysalises, and emerge as adult butterflies.
Of the first group of caterpillars we found on the milkweed plant, one died as a caterpillar, one escaped (we took the terrarium outside one afternoon with the screen removed), one died in the process of molting, and two died after they had molted. Both chrysalises had a fly egg in them, and they were eaten inside-out by a tiny fly larva. The larvae then emerged from the dead chrysalises. It was rather disgusting, but the kids found it very interesting. I'm not sure how many people they told about "maggots eating their butterflies." We had only one caterpillar that molted successfully and emerged two weeks later as an adult monarch.
In the meantime, we found two more large caterpillars and one small caterpillar on the milkweed plant. We brought them inside and placed them in the glass terrarium along with fresh milkweed stalks every day. All three of these caterpillars grew to maturity and molted into chrysalises.
I was fortunate enough to be around with my camera when the last caterpillar molted. Before molting, the caterpillar finds a suitable place to attach himself, and spins a dense ball of sticky silk from which he hangs upside down, in sort of a "J" shape.
The caterpillar noticeably turns green, and soon his skin splits and he wriggles out of it. When the skin has fallen off, he literally turns himself inside-out and the green outside skin hardens into a chrysalis. The butterfly grows inside the chrysalis for 10 - 14 days. Ours averaged about 11 days.
When the butterfly is ready to emerge, the chrysalis becomes clear and you can see the butterfly's colorful wings inside.
When the butterfly emerges, its wings are folded and wet. It takes bout six hours for them to fully stretch out and dry, so the butterfly can fly.
After the butterflies were ready to fly, we took them from the terrarium and placed them in the holly bush just outside our front door. It took only a few minutes for them to fly off in search of flowers. This monarch is a male -- you can tell from the two prominant black dots on his lower wings.
Perhaps we will have more caterpillars this fall, or next spring.
It is the fall generation of monarchs that lives nine months, migrating
to Mexico and then returning to the US and Canada in the spring to
raise their eggs.