Swallowtail butterfly tiger swallowtail), Y-linkage determines whether the females are either wild-type (yellow and black) or melanic (dark melanin replaces the yellow background). This genetic difference stems from the fact that melanism is controlled by a single gene, which controls the level of dopamine in the organism. The enzyme BAS, which assists dopamine in producing the yellow pigmentation, normally found on the wings' background, is suppressed. Without the pigmentation, the butterfly appears mostly black (the melanic form) and is a Batesian mimic of "Battus philenor", the pipevine swallowtail. There are also "Papilio glaucus" that are not wholly black; several possess an intermediate
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