What do Booklice primarily feed on?

Booklice primarily feed on microscopic molds and starchy paste. They thrive in environments where mold growth can occur, such as damp areas with decaying organic material. These pests are especially attracted to starchy substances, which they can digest effectively due to their specialized mouthparts.

In contrast, the other options describe food sources for different types of pests. Plant roots are typically consumed by root-feeding insects, wood and grains might attract other types of insects like weevils or beetles, and animal fibers are typically targeted by fabric pests such as moths. The specific dietary preferences of Booklice make them particularly adept at existing in places where mold and decaying paper materials are abundant, especially in humid conditions. This behavior emphasizes the ecological role of Booklice as decomposers within affected environments.