Monday, July 28, 2008

Monarch Caterpillar - Day 14!!!

Yesterday evening was very exciting. After eating consistently all day, the caterpillar positioned itself on the underside of a large leaf and was very still. Every once and a while it would turn 180 degrees. And finally, we noticed that it had started to create the silk mat or anchor where it would hang to make it's "J hook." This is the position it takes hours to a day before it turns into a chrysalis. It makes the silk mat with secretions from its mouth but it hangs from its tail end.
Here you can see the little white nub from which the caterpillar will make its "J hook"

Here the caterpillar has attached its tail end to the silk mat. The second picture is its head.

This is the "J hook". The caterpillar is hours away from turning into a chrysalis.

I waited until 11:30 pm to watch the caterpillar drop into the "J hook" but when I turned away for about 5 minutes to do some research on the internet, I missed it. It is almost 9:00 am and still no sign of turning. I doubt I will actually catch it on film but I will try.
A few interesting facts about the larva/caterpillar stage:
1. The word larva refers to this stage of growth for all insects that go through metamorphosis. The word caterpillar only refers to a butterfly or moth in this stage.
2. As we witnessed here, when the caterpillar gets too large for its skin, it molts - or sheds its skin. It actually goes through this process five times - these phases are called instars. I must have missed the other times that the caterpillar molted. It is easy to miss because the caterpillar always eats its shed skin before it starts eating milkweed again.
3. Although the caterpillar has six pair of simple eyes called ocelli, its vision is very poor. It depends on its antennae to "see." The tentacles on its rear end are not antennae but they do function as sensory organs.
4. Like other insects, monarchs obtain oxygen through holes in the sides of their thorax and abdomen called spiracles. The spiracles are connected to a network of long airtubes called tracheae, which carry oxygen throughout the body.
This information comes from
Well, this may be more information than you ever wanted to know but I find it fascinating. It's like Mr. Webb's zoology class all over again! Call me crazy but this is the best kind of entertainment af all!

1 comment:

Anna said...

This is super cool to watch. I looked on a milkweed, but I think I need a mentor to help me find an egg. can't wait for the next progress report.