I posted last year about finding what I thought was a Monarch (Danaus plexippus) caterpillar only to discover it was actually a closely-related Queen (Danaus gilippus). You can find that post here.

When I came home on Monday this week, I was walking to the house from the garage and looking at the Antelope Horns (Asclepias asperula) growing along the edge. This plant is a member of the milkweed family and is a food source for Monarch caterpillars. Antelope Horns are plentiful this year even though we haven’t had much rain. I’ve been checking them every time I see one, hoping to find a Monarch caterpillar.

Sure enough, I spotted a plant that had white fluid leaking from the stem where something had eaten a leaf completely off. I bent down to take a closer look and was rewarded with a view of a small caterpillar. I ran into the house and got my camera. I sent the photo to my friend and Monarch expert, Mike Cseri. He’s the one that told me last year that the caterpillar I had then was not a Monarch. This time his response was positive – it was a Monarch!

A Monarch caterpillar on Antelope Horn leaves. The caterpillar’s head as at the bottom

Not wanting to disturb the caterpillar, Mary and I dug up another Antelope Horn and put it a small pot and placed the pot in an unused aquarium. I then broke off the branch the caterpillar was on and placed it on top of the potted Antelope Horn.

The Monarch’s new home. The caterpillar is in the upper center of the photo.

Two days later, Mary found another one! We put it on the same Antelope Horn in the aquarium. Mike told me that judging from their size, it could be about 1 to 2 weeks before they started to pupate. The chrysalis is also known as a pupa. These must have been further along, and of course Mike only had photographs from which to estimate.

When I checked them on Friday evening, they had both attached themselves to a Antelope Horn stem and were hanging in a J-shape. They spun a bit of silk and used that to attach to the stem, so they hang upside down. They also develop a greenish tinge near the head. It’s interesting that although we found the two caterpillars in different parts of the yard, they were about the same age since they pupated at the same time.

Ready to start the transformation.

I didn’t realize the transformation would happen so quickly. When I checked them at noon Saturday, they were both already in chrysalis form! It’s truly amazing that they underwent such a complete transformation in such a short amount of time. Basically, their entire body is dissolved and then rebuilt into a butterfly within the chrysalis.

The chrysalis or pupa.

The caterpillar stage lasts about 2 weeks, so they must have been in our yard for a while before we saw them. The chrysalis stage also lasts about 2 weeks, so I’m going to keep watch and hope to capture the butterfly’s emergence.

The Monarch Watch has more information about this fascinating butterfly.