Puss Moth Caterpillar (Asp) Stings By Robert A Barish, MD, MBA, University of Illinois at Chicago; Thomas Arnold, MD, Department of Emergency Medicine, LSU Health Sciences Center Shreveport Reviewed / Revised Jan 2022 | Modified Sep 2022 View Patient Education Treatment Puss moth caterpillars (Megalopyge opercularis), of the order Lepidoptera, are also known as asps.