There are species of caterpillars (we call worms) that do similar things to Sweet Gum trees here in Georgia....nasty looking concoctions.
“species of caterpillars”
We call ‘em Tent Catapillars here in Ohio. They’ll cover a branch. Fugly! You look in that “tent” and see ‘em all squirmin’ around? Yuck. Fire is my preferred remedy!