Monday, July 22, 2013

Caterpillar Wars

For several years now, I have had milkweed growing in one of my flower beds. This is the host plant for monarch butterflies, so it is often recommended as a native plant for your yard. Even though it grew like a weed and was sometimes unsightly in my planned bed, I left it alone. However after watching it for several years and never seeing any sign of monarchs, I pulled it out. But it came back.(Did I mention the growing like a weed part?) This year, it has been particularly vigorous and was starting to takeover, so I decided that I was going to try to pull it out again or at least try to replant it in a more desirable area. However, when I checked it again this weekend, I found it covered with orange and black fuzzy caterpillars. Upon further investigation, I learned that they were tussock moth caterpillars. There were several descriptions of them, but all included the fact that they are voracious eaters. Maybe this was the natural way that I was going to get rid of the milkweed.

I took Ward out to show him these colorful worms and they had already stripped leaves from several plants and were hungrily working on more. And do know what we saw among them? A monarch butterfly caterpillar! There was no way this one monarch* was going to compete, so we set out to remove as many of the tussocks as we could. The spines on the tussock caterpillars can sting, so we used gloves, a stick, and teamwork to try to rid the milkweed of these hungry eaters. During this tedious process, we found another monarch caterpillar. Wow, two in one year! Now, it is a watching and waiting game to see what develops--monarch butterflies and/or tussocks moths. I know what I'm hoping for.

In addition to being a host plant for butterflies and moths, bees like  milkweed's late spring blossoms. This is when the eggs were probably being laid.

Milkweed Tussock Caterpillars devouring a leaf.

After stripping the leaves from this plant, the tussocks moved onto the next one.

The two monarch butterfly caterpillars we found. Notice the one of the left has eaten away half of the leaf.

If we knew much about monarchs, we would have realized that this skeleton leaf pattern that we saw earlier is common for young monarch caterpillars. At this stage, they don't eat the entire leaf like above.

*Monarchs often only lay one egg per plant to make sure the growing larva has plenty to eat.