Palm leaf skeletonizer, Homaledra sabalella, excrement tubes in which the caterpillars are chewing on a palm frond.

Brown tubes of excrement from a group of palm leaf skeletonizer larvae on the chewed, scraped surface of a palm frond.; Florida Credit: Tim Broschat, University of Florida, Bugwood.org
Credit: Tim Broschat, University of Florida, Bugwood.org