A group of immature bark lice show their characteristic striped abdomens. / Photo Credit: Wisconsin DNR

By Linda Williams, DNR Forest Health specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665

Barklice, sometimes called tree cattle, tend to congregate in large groups on trees, which can lead some people to worry about tree health. However, they are actually quite harmless.

Immature barklice don’t have wings, so you can see their heavily striped abdomens. Adults have dark-colored wings that form a tent over the abdomen. Both immature and adult barklice congregate in groups.

These insects feed on the algae, lichen and other debris that collects on the surface of tree bark. They do not feed on the tree itself.

A group of adult barklice with darkly colored wings held as a tent over themselves. / Photo Credit: Wisconsin DNR

Despite their name, barklice are harmless to people. They are not true lice, so they don’t bite or carry diseases that would cause concern for human health.

Rather than trying to get rid of them, try this playful activity with kids (and adults who are young at heart): when you find a congregation of them, move your hand towards one side of the group and watch as they move in unison to get away from your hand. Congratulations! You’re herding tree cattle!

Barklice are not considered pests, and treatment is generally unnecessary.