The Nice Lice: Bark lice are nothing to worry about

by | Jun 14, 2017

Adult (top) and immature (bottom left) bark lice are nothing to be feared. Their silk webs can become quite large (bottom right), but also pose no threat to tree health. Images: J. Louque, Smithers Viscient, (adult); D. Cappaert, (immatures); C. Hesselein, Alabama Cooperative Extension, (silk webbing).

Every parent dreads the call from their child’s school that lice has been found.  Frantic sessions of chemical dousing, hair combing, and sheet washing typically follow.  Phantom itching leave many paranoid for days or weeks to follow. Altogether, an unpleasant experience.  But here’s a kind of lice not to dread: bark lice.  More and more sightings of these tiny insects on trees are being reported and tree owners all want to know if a chemical treatment should ensue for these lice as well.

Young bark lice are a dark gray or brown color with stripes on their bodies (bottom left in image) and adults have shiny black or mottled wings that are held tent-like over their bodies (top).  They are often spotted grouped together in the bark of a tree.

Bark lice aren’t actually lice at all as they are not parasitic in nature like the more formidable head lice. Bark lice are small insects that spin silk webbing on the tree they inhabit.  The silk webbing can become quite extensive and noticeable, sometimes covering trunk and branches of the tree in sheets of silk.  The webbing will not harm the tree, though some consider it an unsightly addition.  In addition, these are well-mannered guests that clean up their own mess.  The webbing is usually consumed by the bark lice at the end of the season.

Not only do they cause no harm, but many consider bark lice to be beneficial.  They are scavengers that feed on fungi, mold, algae, dead bark, and other organic matter.  As such, management of these tiny critters is discouraged; enjoy the tiny temporary clean-up crew while you have them.  No chemical freak-out necessary!