bark beetle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various small beetles of the subfamily Scolytinae that chew tunnels in the surface wood directly beneath the bark of trees, sometimes causing extensive damage.

from The Century Dictionary.

• noun A member of the coleopterous family Scolytidæ, nearly all of which make burrows between the bark and the wood of woody plants.
• noun Xyleborus pyri, a scolytid beetle which perforates the bark of the apple and pear. Also called apple shot-borer.

from the GNU version of the Collaborative International Dictionary of English.

• (Zoöl.) A small beetle of many species (family Scolytidæ), which in the larval state bores under or in the bark of trees, often doing great damage.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun any of various beetles, of the subfamily Scolytinae, many of which reproduce in the inner bark of trees

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun small beetle that bores tunnels in the bark and wood of trees; related to weevils