From DISCOVER dec. 2002 p 67: "There were plenty of ailing trees, marked by dark cankers,
rivulets of sap, and trails of frass, telltale sawdust left by burrowing beetles."

Not in my dictionary, but sounds reminiscent of German "fressen" verb for animal eating.
(handy word when kids eat like pigs),

Frass - Frass. Click Here. Shop the National Geographic Store. ... Frass. plant fragments made by
plant­feeding insects, usually mixed with excrement. Invertebrate Explorer. ...
http://www.iversonsoftware.com/business/invertebrate/f/frass.htm