They ate up the fennel and we worried about what to feed them next. Turns out they like stuff in the carrot/parsley family and we have loads of queen anne's lace. It took a few hours of adjustment, but the caterpillars transitioned just fine and ate themselves huge.
Then, one morning, we saw one, then another find a quiet place in the jar and start spinning an anchor line from its head to the jar [or stem] upon which it was clinging.
Black Swallowtail butterflies metamorphose upside right. Monarchs hang upside down and metamorphose. It was cool to see the difference.
Here is #1, who found a place to anchor on the side of the jar.
And #2.
A couple days later, this is what we have:
#1.... Notice the split skin hanging just below him. And if you look really closely, you can see all the fine threads anchoring him to the jar.
And here's #2.
They'll sit for about 2 weeks, then emerge.
Since two of them are clinging to fresh greens, we're going to clip their part of the stem off and glue it to a stick.
Note: These guys are green because they're clinging to green stuff. If they had chosen a stick, they'd have turned brown. Camouflage is cool.