Defoliated Barberry Bush
I discovered a mature Barberry bush in my yard completely defoliated. It has some odd brown things hanging on the branches. Then I found another Barberry with something odd growing on it; this bush was beginning to show defoliation. The odd thing on the bush is brown and hangs from a branch similar to the way a bag worm hangs. However, the brown thing is complex with tiny round mud-like balls clumped together and forming a 3-4 inch long thing hanging like a Christmas ornament. What is this? Where did it come from? How can I get rid of it? Is my completely defoliated bush dead? Can this spread to other types of bushes and trees?
There is a barberry webworm whose webbing resembles this. The brown clumps that you see in the first photo are pupal cases made by the worm, constructed of leaves, frass (fecal material), and other materials. There is not much information about this insect. Here's some: http://w3.biosci.utexas.edu/prc/DigFlora/BERB/Webworm.html
Barberry is a very problematic non-native invasive plant in Maryland and the entire east coast. It is taking over our parks and natural areas and creating a health problem because the humid, dense environment it forms is a nursery for deer ticks. Even worse, research shows that those tick have a higher percentage of infection with Lyme disease. Research is ongoing.
So, we recommend that homeowners not plant and do remove any barberry that forms berries.
From that perspective, the webworm may be a blessing in disguise if it starts killing the barberry in our parks. It will not feed on other species besides barberry as far as we know.