We received a question a few days ago about small worms that spin a “thread like line from vegetation.” (The worms’ threads are probably found mainly on trees, and hence our title, but they could be on other plants as well.) The reader lives in Arizona, and only sees the thread-spinning worms at night, or at least this is when the worms are believed to be creating their threads. (The reader is ambiguous on this point.) The reader was only preoccupied with identifying the small worms, so we’ll limit ourselves to this matter, only concerned with the question “what are the small worms that spin threads and hang on trees?”