Trees with smoother bark are better at repelling attacks by mountain pine beetles, which have difficulty gripping the slippery surface, according to a new study by the University of Colorado Boulder.

Clockwise from top left: (1) Two lodgepole pines growing side-by-side with notably different bark textures, (2) a rough-barked limber pine that has been attacked by bark beetles, (3) a limber pine ...

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