"Cat's cradle"

At our house, the term "cat" is used both for the four representatives of felis domesticus and as a verbal shorthand for "caterpillars," so I've misapplied the old phrase "cat's cradle" to title this post about the chrysalis of a Clouded Sulfur butterfly (Colias philodice).

One of the things that fascinate me regarding butterflies is the process of metamorphosis.  The transformation takes days, and during this time the caterpillar has to secure itself somewhere.  Some, like the Monarch, glue themselves to a surface and hang vertically:

- while others, like the Black Swallowtail shown here -

- and the Clouded Sulfur "proceed to anchor themselves with a silk attachement at the base and a remarkable silk strand enclosing the upper thoracic region, so that the pupa is suspended like a mountain climber hanging from a cliffside in a sleeping bag."

I have never been lucky enough to see this while it was happening, so I don't know how it manages to spin the silk around its body like that.

I also think it's very cool that the completed chrysalis (second photo from the top) has the shape and color of a leaf of the vetch on which it was created, helping to camouflage it during the time the larva is so utterly defenseless.

More about the sulfur tomorrow or this weekend.