Eastern Tent Caterpillars are the larvae of the Lackey Moth.
The moth lays its eggs around a tree branch and the caterpillars hatch from
eggs the following Spring when leaves unfold. They go through about a half
dozen larval stages of development called instars. They make the silk tents you probably have noticed in the branches of trees in
the Spring. During the final stage, they consume most of the food of their whole
life cycle, and may nearly defoliate their tree, which likely will recover. They stay in their tent to
keep warm, move around the tent to regulate the temperature, and whenever it gets too warm they move to the outside surface of the tent
to cool down, as you see in this image.
After about two months they are in their final larval stage
and leave their tree to find protected places to spin their cocoons. It was at
this stage that I was preparing to photograph an adult caterpillar on a sidewalk beneath
its natal tree. I was positioning my tripod when I noticed the caterpillar was
on its back and not moving, apparently dead. I felt bad because I assumed I had
killed it with my tripod. To
record its now visible legs I snapped this picture.
A few seconds later a Carpenter Ant, which must not mind dead prey, grabbed the carcass and
started to drag it away. Suddenly the caterpillar came to life, flipped over
and violently shook the ant off, after which I took this photo.
I had never
heard of a caterpillar playing possum like this. I did a little research and
found that some caterpillars and other insects discourage predators by playing
dead - a strategy called thanatosis.
To complete the story, a female caterpillar would go on to
spin a cocoon and in a couple of weeks emerge as an adult moth full of eggs. Then within
about 24 hours it will secrete pheromones to attract a male moth to fertilize the eggs, lay the eggs
on a branch, and die, thus completing this life cycle. The male moth may go on to fertilize multiple egg masses over a period of more than a week.
