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) 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 brown house moth, will attack cloth bindings. Leather-bound books attract various beetles, such as the larder beetle, drugstore beetle and the larva of the black carpet beetle. Larval death watch beetles and common furniture beetles will tunnel through wood and paper (if it is nearby the wood). A major book-feeding insect is the book or paper louse (also known as booklouse or paperlouse). These are tiny (under 1 mm),