Occasionally we see strange little caterpillars dragging what looks to be some kind of shell or case around with them. Here’s one moving precariously across a wall:

The clothes peg at start and end of the video is for scale. The caterpillar and its case are just a few millimetres long. The head and thorax of the caterpillar stick out at the top of the case, with the rest of the body inside the case. There’s nothing holding the case against the wall except the caterpillar’s six tiny legs at the top!

After seeing the above caterpillar yesterday, I searched the internet to find out what it was. It looks to be a caterpillar of a case moth (Psychidae), also called a bagworm.

Then I remembered another odd case that I’d seen on the wall of our house a year or so ago. That turns out to be a case moth’s case too. This one is  more decorative than the one above:

Evidently the caterpillar pupates within the case, and sometimes the female moth even lives her entire live within the case.

The Butterfly House has more pictures of the decorative cases of the case moth.