Insects and Spiders - Butterflies, Moths, and Caterpillars : Western Tussock Moth
Orgyia vetusta
The first one of these that I saw was on a Pacific Madrone tree, and I didn't see it until I looked at the photos at home. I went back to look again with no luck. But then another time I found one of the caterpillars on the temporary sheep fencing.
One day I found some really strange things on an oak tree. Turns out they are Western Tussock Moth cocoons! Female Western Tussock Moths are flightless, and after they lay their eggs, they cover the eggs with their setae--the hairs covering their bodies. The eggs begin to hatch in in early spring, and the larvae eat the remaining egg mass. Sometimes they use "ballooning" to set out on their own in the world. (For more information on ballooning, click here. Part way down the page it will talk about spiders ballooning.) Adults emerge in springtime, but only the males become recognizable as moths.
I'm not sure what that white thing is, but this cocoon looks pretty empty.
Two cocoons here with what appears to be a spider lurking between.
Spider legs and a close-up of one of the cocoons. It's hard to tell if there are exuviae (the larval covering) in the hairs there or not.
Another cocoon that might have something inside.
Notice in the circle what likely is a shed skin of the caterpillar during one of its instars.
