Meet the bark louse

For the past year, these Friday Profiles have offered deep dives on people, places and products, but I think there’s one more “P” to add to that list - Pests.

This week, I’d like to spotlight some often-misunderstood good guys in the pest world – bark lice.

I get dozens of calls to the GardenLine radio show, especially during the summer, asking, “What’s the creepy, silky web covering the trunk of my tree?”

First, don’t panic. Bark lice are beneficial insects. They’re not in any way a threat to the health of your tree. The great Bill Zak - the legend who preceded me as GardenLine host - wrote in his book, Critters, “… as mysteriously as the web appeared on your tree, it will also disappear within a couple of weeks.”

I suppose what really freaks people out is how bark lice appear so suddenly … frequently overnight. You walk out to get the morning paper, and there they are. Just yesterday, the tree looked perfectly normal.

Bark lice are considered truly beneficial insects because they actually clean up the bark of a tree, scouring it for fungi, spores, pollen, lichen and other debris. While dining, they spin a web for protection. Once they finish with a tree and move on to their next temporary home and food source, the web just disintegrates, usually within a week. And they are known for favoring the trunks of hardwood trees, especially oaks.

The bottom line is you don’t need to do ANYTHING! I know many people blast the webbing off with a hose or a pressure washer, but that’s completely unnecessary. And you’ll find that sprayed-on chemical insecticide simply bounces right off the webbing.

So, next time you see trees covered with an eerie web, remember that it’s the often-misunderstood bark louse just doing his or her thing.

But here’s something that IS a problem: webbing in the leaves of your tree. That’s a form of webworms or tent caterpillars, and they do need to be controlled. We have information on combating them here.

GardenLine Profiles

GardenLine Profiles

Welcome to the GardenLine Friday Profiles. Each week, we focus on a nursery, garden center, feed store or hardware store, and we occasionally spotlight individuals who are important in the GardenLine world. Plus, we periodically focus on specific... Read more


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