Webbing on Plants: Diagnostic Guide

Webbing on plants — how to distinguish spider mite webs, tent caterpillar silken tents, fall webworm nests, and actual spider webs, with the right response for each.

The diagnostic decision tree

Step 1: Where is the webbing located?

• On or between individual leaves, especially leaf undersides: spider mites
• In the branch crotch (fork between major branches), before leaves are fully out (spring): eastern tent caterpillar
• At the tips of branches, enclosing leaves inside a bag-like structure (late summer/fall): fall webworm
• Loose, irregular silk threads between stems and branches with no leaves inside: spider (beneficial)

Step 2: Is there leaf damage within the webbing?

Spider mite webbing is incidental — the damage is stippled, bronzed leaves. Tent caterpillar and fall webworm nests contain caterpillars feeding on enclosed foliage; heavy defoliation may occur inside or near the nest. Spider webs contain no feeding damage — they're traps for prey insects.