Insect morphology least three different positions: prognathous, opisthognathous, and hypognathous. In species with prognathous articulation, the head is positioned vertically aligned with the body, such as species of Formicidae; while in a hypognathous type, the head is aligned horizontally adjacent to the body. An opisthognathous head is positioned diagonally, such as species of Blattodea and some Coleoptera. The mouthparts vary greatly between insects of different orders, but the two main functional groups are mandibulate and haustellate. Haustellate mouthparts are used for sucking liquids and can be further classified by the presence of stylets, which include piercing-sucking, sponging, and siphoning. The stylets are
Bookworm (insect) soft-bodied wingless Psocopterans (usually "Trogium pulsatorium"), which feed on microscopic molds and other organic matter found in ill-maintained works (e.g., cool, damp, dark, and undisturbed areas of archives, libraries, and museums), although they will also attack bindings and other book parts, making the booklouse not a true louse. By the 20th century, modern bookbinding materials thwarted much of the damage done to books by various types of book-boring insects. Bookworm (insect) Bookworm is a popular generalization for any insect that is said to bore through books. True book-borers are uncommon. Two types of moths, the common clothes moth and the