Bark Silk. Bark lice are small insects that spin silk to create dense, protective sheets on tree trunks and branches. These insects, also called psocids, are harmless and beneficial, as they feed on algae, fungi, and other organic debris on the bark, effectively cleaning the tree. Part of my ongoing project titled Barkscapes. Taken in Edith Moore Nature Sanctuary, Houston, Texas. Nikon Z50-II, 250 mm, 1/60, f/11, ISO 1000.