Two years ago, Bob and Mary Dye, who live at the end of Elk Ridge Trail, noticed a strange, cocoon-like webbed structure at the very tip-top of one of their ponderosas by their house. They were new to the ranch, having bought Gene and Sue Downs' house, so they asked their neighbors if they knew what this alien thing was. None of them had ever seen such a thing, so they suggested that the resident retired ranger be consulted. That's me. But I didn't have much luck identifying the thing at that time.
Then at the beginning of this spring, I noticed something similar in one of the ponderosas in front of my house. I thought it closely resembled a silken beehive constructed around the topmost growth on the pine. Shortly after this, I got an inquiry from Dave and Shari Schroepfer on Spruce Lane that they had one. So I decided to get serious about nailing down the identity of this alien critter.
My favorite web site for this sort of thing is the Colorado State University Cooperative Extension (www.ext.colostate.edu) I didn't see what I was looking for, so I submitted the question to their question and answer people. In a few days Dave Leatherman, CSFS Entomologist responded with the following:
This is Tiger Moth (Lophocampa ingens). This insect is unusual in that it makes tents on most of our conifer trees (pines, Douglas-fir, rarely others) and that the caterpillars feed during the late winter and spring months.
Apparently the tent affords them insulation from winter temps and they are probably loaded up with their own forms of antifreeze. The caterpillars finish feeding on needles about this time of year and then wander down from the top of the tree and make cocoons near the ground. The moths appear in about a month and are medium-sized, off-white and yellow-brown with large polka-dots on the wings. Usually this insect only feeds on the very top leader and may kill it, but that is the extent of the damage. Additionally, the caterpillars are covered with hairs that are quite annoying to the human skin, resulting in a rash if handled. Unless this is a Christmas tree plantation or some other type of tree where the top is very valuable, I wouldn't worry about it, and would just give the caterpillars some space if you see them wandering around.
So now we know.