A Visit From A Queen

I was checking our chickens for eggs and to give them water when I noticed this caterpillar very near their coop.

It was feeding on an antelope horn which is a native plant and very common on our property. It is a member of the milkweed family, so I immediately thought it was a Monarch caterpillar which I know feed exclusively on milkweed. You can see in the photo that it's been chewing its way down the plant. The upper leaves are completely gone and you can see the white milky fluid, which gives the family its name, leaking out. The caterpillar is about 1 inch long.

I showed the photo to a friend of mine, Mike Cseri, who is my local expert on Monarchs. He's participated in the Monarch Watch and has raised Monarch butterflies from eggs. He took one look and said "That's not a Monarch!". I said "Are you sure?". I should know better than to question an expert.

He pointed out that the caterpillar has six "antenna" and that Monarchs only have four. The appendages are not really antenna, but they do function as touch sense organs. Monarchs have four, two at the front and two at the back. This caterpillar has 6 antenna, the extra pair are along the body, nearer to the head. He didn't know what it was, but was positive it wasn't a Monarch.

This started a frantic search on the Internet to try to identify the caterpillar. I finally came across photos of a Queen caterpillar which looked like a match. Mike reviewed them and agrees. Queen Butterflies also live in the area, eat milkweed and are closely related to Monarchs.

Both of these butterflies' caterpillars have an interesting and exclusive diet. Milkweed is poisonous, but the caterpillars are able to consume vast quantities of it in preparation for their metamorphosis into the adult form. Not only have they evolved protection against the poison, but they sequester the chemicals into their body and use it as a defense against predators. It's thought that the bright colors of the larva and adults serve as warnings to predators.

I noticed when I let our chickens out to roam our yard and feed on whatever they could find, mainly grasshoppers, they did not eat the Queen caterpillar even though they walked right by it. Perhaps the warning signs were working.