Even after all these years of recording insects in our yard, it is still possible to discover a few new ones.
Take last week. I found this tiny caterpillar feeding on a Thurber's cotton leaf.
With a little research I found out it is the larva of the cotton leaf perforator moth, Bucculatrix thurberiella. The youngest caterpillars mine the leaves on the inside, creating tiny tunnels. When they get larger, they stay on the surface chewing out window panes of leaf tissue.
You can see photographs of the adult moth at Discover Life.
Am I worried about this caterpillar feeding on my plant?
Well, no. First of all the caterpillar is very small, and the plant is very big. Secondly, it is winter and the cotton plant is losing its leaves anyway. What difference does it make if a caterpillar takes a few bites before the leaf falls off?
This is what the Thurber's cotton plant looked like earlier in the year:
You can see more at this related post about Thurber's cotton.