Anise Swallowtail chrysalides

[Lisa Millbank]

I've been very busy lately and haven't sent out an update on the Anise
Swallowtail caterpillars in almost 2 weeks. First, I appreciate all of
the comments and caterpillar stories people have sent me, and although I
didn't have time to respond to all of them, I really enjoyed reading
them. I think it's great that so many people are so interested in insects.

The caterpillars were in their fifth instar, and on Thursday, 9/11, the
larger of the two caterpillars stopped eating and "purged" its gut of
undigested fennel. It began crawling around a bit frantically because
it was looking for a place to pupate. The caterpillars are nearly
blind, so they just feel their way around, trying to leave the host
plant and go to a relatively secure location. It's a similar thing when
we see "woolly bears" (Isabella Moth caterpillars) crawling around,
during their search for a place to spin a cocoon. We placed the
caterpillar in a toilet paper roll with a piece of toilet paper secured
over the top. By the next day, that caterpillar had fastened itself to
the toilet paper. It hooked the end of its abdomen into a little silk
button, and then spun a silk harness around its "shoulder" area.

On Saturday, 9/13, it had turned grayish, as its old skin was starting
to separate. Eventually, it wiggled and contracted enough for the skin
to split and peel off its body. It was now a chrysalis, but it still
could wiggle its abdomen until a couple of days later when it hardened
up. The second caterpillar was a couple of days behind, but went
through the same process at about the same rate. This one pupated on
the cardboard tube itself. The two chrysalides have different
pigmentation that matches the way they were as caterpillars, with one a
bit darker than the other.

In the attached pictures, you can see the oval-shaped spiracles
(respiratory holes) along the side of the chrysalides, and their silk
harnesses. The head is toward the top. They seem to have very good
camouflage for waiting out the winter on tree bark.

Anise Swallowtails overwinter as a chrysalis. There's not enough time
for these two to hatch into butterflies, mate, produce eggs, and have
caterpillars reach the pupal stage before it gets too cold, so they're
going to take a long winter's nap and emerge in spring.

There appears to be some controversy in the world of butterfly-rearing
when it comes to overwintering chrysalides. Some recommend keeping them
in an unheated shed, while others say the refrigerator works much better
(a shed can get too warm and cause premature emergence). Some advise
misting the chrysalides with water on occasion, while others say this
causes mold. I've decided to refrigerate them in a large, airtight
container where the humidity and temperature will be constant until we
take them out in spring. While in diapause, they need very little
oxygen, and there's more than enough inside the container.

I have to say, these pupae are the quietest, cleanest little pets we've
ever had, though they don't seem very cuddly. I hope all goes well and
we get a couple of adults in April!

Lisa Millbank
www.neighborhood-naturalist.com