bark louse

from The Century Dictionary.

• noun A minute insect of the genus Aphis that infests trees; an aphid.
• noun An undetermined lecanine, Lecanium sp.
• noun A diaspine scale, Aspidiotus ancylus.
• noun A diaspine scale, Aspidiotus uvæ.
• noun A diaspine scale, Aspidiotus pyri.
• noun A diaspine scale, Diaspis pyri.
• noun The San José scale, Aspidiotus perniciosus.

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

• (Zoöl.) An insect of the family Coccidæ, which infests the bark of trees and vines.

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

• noun An insect of the family Coccidae that infests the bark of trees and vines.

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

• noun any of several insects living on the bark of plants
• noun any of several insects living on the bark of plants