Viceroy Update: Caterpillars have emerged!

The hibernating Viceroy caterpillars have emerged! In a previous post I wrote about the earlier stages of their development. I took this series of photos of one of the same caterpillars over the last week. It is interesting that it still returns to the hibernaculum to rest since it has emerged. It has molted at least once since it emerged (they overwinter in their third instar [molt]), so it is in fifth instar by now. 

You can see one of its old skins just above it.

 It has turned a grayish-green color now, which means it is about to pupate.

Notice how this caterpillar resembles a twig or bird dropping. If that isn't enough, the willow leaves and other Salicaceae these caterpillars feed on contain salicylic acid, which makes these larvae bitter and distasteful to predators.

I'll be out of the country for the next ten days, but I hope to update you on its progress after I return. In the meantime, pending internet availability, I may post some pictures from the other side of the world.

Joseph

Previous post in this series: Viceroy Hibernacula: Something about butterflies for a change

Viceroy Hibernacula: Something about butterflies for a change

Ever wondered what butterflies do during the winter? A few migrate each year (like the Monarch), but most overwinter in our area, either as adults or larvae. The Viceroy, Limenitis archippus, has a nifty strategy to survive. When these caterpillars molt for the first time they begin monitoring daylight. They can sense when the days are getting shorter, and each caterpillar makes the decision whether to enter diapause (dormancy) or to continue developing. With the approach of fall, most will enter diapause and build hibernaculum; small cocoon-like structures that protect them during the winter.

I raised several Viceroys last summer and knew where I might find these dormant caterpillars.

This may just look like a dead leaf, but it has a little caterpillar inside! Well, probably, I didn't actually rip it open to check.

Yesterday I ventured out and found a half-dozen or so hibernaculum on a small willow near our farm. The key to finding them is to look for rolled-up, trumpet shaped dead leaves that are tied to the twig of a willow tree.

When the weather warms up in the spring, these caterpillars emerge ravenous, and do little but eat until they pupate and finally emerge as a butterfly.

The Viceroy caterpillar

The chrysalis

And the butterfly (Photo by Andrew)

The adult Viceroy is thought to be a Mullerian mimic of the Monarch. While not tasty itself, it mimics the pattern of the more poisonous Monarch, so as to not be eaten by birds and other predators.

If you want to learn more about raising butterflies, you should check out this very helpful site.  I successfully raised several species last summer and hope to try several new ones this year.

Joseph