Abandoned nurseries

Along the fence around the campsites at Bull Canyon, a small stand of aspens has sprung up. Most are still under 8 feet tall. And most, this year, are sporting lumpy blackish growths along the stems.

What lived inside this? About 2 inches across.

I broke a few off. They were all hollow and dry, as thin and fragile as eggshells. There was no sign of their previous occupants.

This one seems to incorporate a dried leaf.

I looked up aspen galls, and found leaf galls;, small blobs that grow right at the base of the leaves and twig galls; small, smooth balls lined up along a twig, but nothing like these.

Most of the galls had several holes that looked more like chickadee predation than insect exit holes. I have watched chickadees with thimbleberry galls in the winter, pounding away at them until they crack open. Somehow they know there's good meat inside that hard casing; maybe the larva inside moves around, makes some sound that we can't hear, but the chickadee can.