Bark Lice Webbing on Oak Trees: Harmless but Startling

What Is That Ghostly Webbing on Your Oak's Trunk?

If your mature live oak is draped in fine, silky webbing covering the bark — but not the leaves — you're likely hosting a population of bark lice (also called psocids). While the "ghostly" appearance can be alarming, these tiny insects are harmless cleaners, not pests.

Understanding Bark Lice

Bark lice feed on algae, fungi, lichens, and dead bark tissue — essentially power-washing your tree's bark for free. They spin delicate webbing for protection, which can envelope the trunk, major branches, and even exposed roots when populations boom. High humidity favors population spikes, making the webbing suddenly noticeable.

No Treatment Needed

The webbing is fragile and naturally weathers away. Bark lice cause zero damage to the tree's health, foliage, or structure. No control is recommended. In fact, they're beneficial — nature's cleanup crew for oak bark.

If You Really Want Them Gone

For purely aesthetic reasons, you can:

• Spray a mild soap solution (2 tablespoons liquid dish soap per gallon of water) on the webbing.
• Blast the trunk with a strong water stream — though this only temporarily removes webbing; the lice will rebuild within hours.
• Apply a labeled insecticide to the bark, but this is rarely justified.

Bottom Line

Relax. Your 40-year-old oak is fine. The webbing is temporary, the insects are beneficial, and no action is required. Enjoy the free bark-cleaning service.