On August 28th, I found a White-marked Tussock Moth caterpillar slowly descending a tree in the Ile Bizard nature park near Montreal. It paused beside a raised piece of bark and stayed motionless for a long time which allowed me to get many photographs of it. I find it a particularly striking caterpillar and was excited to find it.
Then on September 15th, I returned to the park
and whimsically decided to visit the same tree to see if, by chance, the
caterpillar was still there. Instead, in
the exact place where the caterpillar paused, I found an odd looking cocoon
with black hairs sticking out and a frothy substance stuck to it. I decided to check the Internet for images of
the cocoon of the White-marked Tussock Moth and was surprised to learn that it
was indeed the cocoon of the very caterpillar I had seen earlier!
I also learned that the caterpillar was a female who,
when she emerges as a moth, lays her eggs on the cocoon which are encased in a foam
which hardens and allows them to over-winter.
She must attract males soon after emerging, then mates, and lays her
eggs in a very short time frame. Another
fascinating fact is that she has rudimentary wings and cannot fly.
Since reading that the moth stays in the vicinity of the
cocoon, I was disappointed not to find her on the tree but I will look for
these cocoons next year and hopefully find a moth then.
I also found another cocoon in a different park a few days later, but alas, no moth:
This link has more information and photos: http://www.abundantnature.com/ 2012/11/eggs-on-hairy-cocoon. html