Eastern Tiger Swallowtail

Click on all the photos to enlarge.

This Eastern Tiger Swallowtail caterpillar (Papilio glaucus) showed up on my garage door last evening. Normally when I see them they are very green but this little critter had already turned brown to blend in with the surrounding door. According to David Wagner in Caterpillars of Eastern North America, this is called countershading, “a strategy among caterpillars that helps them avoid detection by birds and other visual predators.” He goes on to say, “Countershading is achieved with graded lightening of the sides of the body: those portions of the body receiving the least amount of light, and that would normally appear darkened, end up resembling the dorsum (bottom).” You can certainly see that at work here. In fact the modeled color on the back and sides looks almost like the side of the garage door. When they are real young (early instar) they look like bird droppings. Just before pupating and making a chrysalis they turn this brown color.

You can still see the fake eye on the top of its body. The head is actually that smooth brown area at the very front hidden well under the fake puffed up head. I think this one must have crawled over from the Tulip Poplar tree at the end of my driveway. They like to munch on those as well as magnolia, sweetbay and cherry trees. This is the last brood of the season and it will winter over as a chrysalis and emerge as a butterfly in the spring.

It must have just arrived at my garage door about the same time I had because it was just lightly attached. I moved it over to the side of the house because it would never survive the constant up and down of the door. Last week I found a toad at the back door and this week a cool caterpillar so it just goes to show you never know what you will find just outside your door.

Find more fun and interesting critters at Camera Critters.