Here is a photo of a Pitch Twig Moth, or Pitch Nodule Moth (Retinia sp.), which I reared from one of those lumps of pitch.
Now for the story of the life of a pitch nodule maker.
It would seem that living hidden in this resinous mass affords the larvae some protection from predators.
The moths have a two year life cycle and that is evident in the photo below... the older pitch has a darker look and notice that the twig is swollen, or deformed, opposite (under) the pitch blister.
In the photo below, I pulled back the pitch mass to reveal a caterpillar. The pitch nodule maker is in its 'ditch' on the left side of the picture. Notice the silk webbing between the caterpillar and the pitch in the foreground - the caterpillar must use silk to manage the sticky, oozing pitch.
The inside of the pitch nodule is made up of minute balls of pitch and frass.
I found that the larvae had begun to pupate around mid May.
About a day or so before the moths emerged from their pupae, each pupa wiggled completely out of the pitch mass and dropped to the ground. At least that's what they did in my rearing containers. Perhaps in the wild they wiggle out only part way before the moth emerges. Anyway, a couple of weeks after pupating the adult moths emerged from the pitch blisters.
Here is a photo of a Pitch Twig Moth at home on the tip of a pine needle.
Soooo, there you have it.... the story of the pitch nodules I found when I turned aside from the trail on a cold January day.
Actually, there might be a bit more to the story. I noticed some small orange things on the surface of some of the pitch nodules. Right then and there I decided to see if I could figure out what they are. My first thought is that those look like fruiting bodies of a fungus that grows in the pitch.
It seems there is always more to the story than meets the eye....