Confusion sometimes surrounds the various insects which use silk to build shelters for themselves.
I thought a short discussion about the ones we commonly see in Ohio might help clarify things a little. Beginning in late May through mid-June, larvae of this native moth feed on arborvitae, junipers, pines, spruces, and many deciduous trees. Larvae build loose silken bags which cover their entire bodies. Bags are camouflaged with pieces of plant material, and may be mistaken for natural parts of the tree. When larvae are fully grown, their protective bag is 1.0 to 1.5 inch long.