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Extension > Garden > Diagnose a problem > What insect is this? > Insects found indoors > Beetles, bugs, ants, and other insects without obvious wings - Under 1/4 inch long > Book louse

Book louse 1
Photo Credit: Jeff HahnBook louse 2
Photo Credit: Ken Gray Collection, Oregon State Univ.

Book louse
Size: Up to 3/16 inch long.

Where/When: Found outdoors, on tree bark, plant foliage, or under stones. Found indoors in damp, warm, undisturbed places where mold and fungi are growing, especially during spring and summer.

Significance: Nuisance. They are harmless to people and essentially harmless to property; on rare occasion, they can damage some paper products.
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