Skip to content

Not far from where I found the cellar spider last week, I found this caterpillar feeding on a small ironwood tree. Instead of being alarmed that a caterpillar was eating my plant, I was actually pretty excited. I was pretty sure it is the larval form of the Mexican yellow, a very pretty butterfly. If not, then it is a closely related species.

caterpillar

If you are interested, here is a link to the Butterflies of Southeastern Arizona page which shows what the caterpillar might turn into, the Mexican yellow, Eurema mexicanum.

And here is their picture of the larva stage. Do you think it is the same kind, too?

The caterpillar was over an inch long, probably nearly mature. The next day it was gone. Hopefully it crawled away to form a chrysalis in a protected place and I'll be showing you a photo in a few weeks.

This morning when I was talking on the phone with my sister outside, I noticed a spider wrapping up a fly it had caught in its web. I recognized it immediately as a cellar spider, Family Pholcidae, because of its slender body, long legs and the tangled shape of its web. It also has dark markings on the underside of its body.

The larger cellar spiders common around homes in the Southwest have been introduced from Europe. This one looks like the marbled cellar spider, Holocnemus pluchei, because of the marbled white and pinkish-red pattern on its abdomen.

cellar spidercellar spider 2

We have a community of cellar spiders that live on the outside of one of the windows where we watch our bird feeder. When the feeder is quiet, we watch the spiders instead.

After finding the infrared photographs last week of a cat with hot feet, I started thinking about the temperature of body extremities in cats. You see, there is a “cool” example of how the environment can change what an animal looks like and it involves cats (although the same phenomena is also found in rabbits and mice.)

Ever seen a Siamese cat? These cats are light colored with darker feet, ears and noses. It turns out their color is due to a mutation in the gene that produces brown color (the protein melanin), called the Tyrosinase gene. At normal body temperatures the coat color of an animal with the Siamese variation is light. At slightly lower temperatures, such as occur on the animal’s extremities, the normal dark brown pigments are produced. Conventional wisdom says when a Siamese cat is raised in a cold climate, such as Northern Canada, it will have more extensive brown on its legs, tail, nose and ears than a Siamese raised at the equator.

Now go back and look at the infrared photograph of the cat at the infrared zoo. Are the extremities cooler? Seems to be a contradiction here. Any ideas why? Where do you think this Siamese cat in this picture from Wikimedia Commons was raised?