Which pest causes defoliation and silk/webbing on landscape trees, signaling a common Florida issue?

• A. Scale insects — honeydew and sooty mold on leaves.
• B. Bagworms cause defoliation and silk/webbing.
• C. Aphids cause honeydew and mold.
• D. Spider mites cause stippling.

Answer: (B)

Defoliation accompanied by silk or webbing on landscape trees is a giveaway sign of bagworms. These caterpillars build protective silk bags from bits of foliage and weather debris, then feed from inside the bags. As they grow, they strip branches of leaves, causing noticeable defoliation and a network of silk on the tree, which is especially common in Florida’s warm climate. That combination of leaf loss and visible silk webs is the hallmark that sets bagworms apart from other pests. For comparison, scale insects produce honeydew and sooty mold on leaves, aphids also produce honeydew and mold, and spider mites cause stippling and fine webbing but not the distinctive hanging bags and heavy defoliation seen with bagworms. In Florida, look for small bag-like cases hanging from branches; early detection is key—remove bags by hand or prune infested shoots, and consider targeted insecticides such as Bt kurstaki or spinosad when larvae are young to keep populations in check.