Bug Identifier

Centipedes, Millipedes & Crawlers

Booklouse

Liposcelis spp.

024
Body length in millimeters. Shaded bar shows the typical adult range.
Scientific nameLiposcelis spp.
GroupCentipedes, Millipedes & Crawlers
Size1–2 mm (up to about 0.08 in)
Colors White, Tan and Gray
Legs6 legs
WingsNo (as usually seen)
Where foundPantry or stored food, Basement or garage and Indoors, anywhere
Most activeSpring, Summer, Fall and Winter
BitesNo
StingsNo
Risk levelHarmless

How to identify it

The booklouse is a tiny member of the centipedes, millipedes & crawlers group. Wingless ground crawlers, many with far more than six legs. Check for these three features:

  1. Very small, pale, wingless body
  2. Enlarged hind legs and fast, jerky movement
  3. Found on old books, boxes, windowsills and grain

About this bug

A tiny, soft, pale insect that feeds on microscopic mold growing on paper, cardboard and stored food. It thrives in humid rooms and new construction.

You'll usually find booklice in pantries and stored food, in basements and garages and indoors. They are most active in spring, summer, fall and winter.

Is it dangerous?

Booklice don't bite and aren't true lice; they indicate high humidity and mold.

Our rating: Harmless, meaning it poses no real threat to people, pets or property.

When you'll see booklice

Booklice are most active in spring, summer, fall and winter. In spring, overwintering adults become active and many species lay their first eggs. Summer heat speeds up development, so populations can grow quickly. In fall, many bugs look for shelter, and some move toward or into buildings. In winter, activity continues mainly indoors in heated spaces.

Typical places to check: pantry or stored food, basement or garage and indoors, anywhere.

About centipedes, millipedes & crawlers

The booklouse is one of the centipedes, millipedes & crawlers. This group gathers wingless crawlers that people often lump together: centipedes, millipedes, silverfish, earwigs, springtails, booklice and pill bugs. Most need high humidity to survive and dry out quickly in dry air.

Because moisture is the common thread, a dehumidifier and fixed leaks often do more than any insecticide.

What to do about it

  1. Lower indoor humidity below 50 percent
  2. Throw out moldy boxes, papers and food packages
  3. Improve ventilation in closets and storage areas

Bugs that look similar

Bed BugCimex lectularius4–7 mmCan bite or sting

Group: Booklouse belongs to centipedes, millipedes & crawlers, while bed bug belongs to true bugs. Wingless ground crawlers, many with far more than six legs.

SpringtailCollembola class1–2 mmHarmless

Color: Booklice are white, tan and gray; springtails are gray, black and white.

Frequently asked questions

What does a booklouse look like?

Very small, pale, wingless body. Adults measure 1–2 mm (up to about 0.08 in).

Does the booklouse bite or sting?

It does not bite. It does not sting. Booklice don't bite and aren't true lice; they indicate high humidity and mold.

Where do booklice live?

Booklice live in pantries and stored food, in basements and garages and indoors.

When are booklice most active?

Mostly in spring, summer, fall and winter.