Insects dangerous to museum collections are illustrated and described, including the clothes moths, carpet beetles, silverfish, firebrat, booklouse, cadelles, hide beetle, and larder beetle. Favorable growth environments and methods of control are covered. Among effective control techniques described are fumigation and fogging; dangers of fumigation are emphasized. Also described are use of spray can insecticide, moth crystals (paradicholorobenzene and naphthalene), the fumigation box (with construction details and drawings), impregnated strips, and dry cleaning. The problems resulting from the bans on use of most residual insecticides (such as Aldrin, Chlordane, Diazinon, Dichlorovos, Dieldrin, DDT, Endrin, Heptachlor and Lindane) are discussed. Timing of treatments to coincide with the vulnerable phase for the species involved is essential. A table plots the vulnerable and absolute vulnerable phases of various insects: two treatments 20 days apart (under proper temperature and humidity conditions) will kill most insects; exceptions are mentioned.