Naphthalene in the form of flakes (preferably) or moth balls is effective when used at the rate of one-half to 1 pound to each 10 to 13 cubic feet of space. It is always better to use a larger rather than a smaller quantity of these crystals Great care should be exercised to keep tightly closed the trunks or chests of clothing with which the naphthalene is stored. Naphthalene in chests opened frequently or those carelessly left open for hours at a time, or in chests with large cracks or warped covers, is not to be depended upon. Naphthalene should be of good grade. It is best to purchase it put up in unbroken tin cans of 1 pound or more capacity. Remember that naphthalene kills all stages of the carpet beetles by means of the fumes given off during the slow evaporation of its crystals and it is essential that these fumes be closely confined. Naphthalene in bureau drawers, in closets frequently used, scattered upon closet shelves, or beneath carpets is not to be depended upon for absolute protection.
Paradichlorobenzene crystals are similar in general appearance to those of naphthalene. The fumes given off by the slow evaporation of the crystals in a tightly closed container will kill all stages of the carpet beetle, if about 1 pound of crystals is used for each 10 cubic feet of space.
Camphor is not as quickly effective against all stages of carpet beetles as are naphthalene and paradichlorobenzene. Its action is slower. Use from one-half to 1 pound for each trunk of about 10 cubic feet capacity.
Chests made of red cedar, popularly known as Virginia[11] or Tennessee red cedar, if well constructed, will kill the very young larvæ of carpet beetles. They will not kill the beetles, the older larvæ, or the pupae, nor will they prevent the eggs from hatching. The writer has known larvæ of the black carpet beetle[12] to remain apparently unaffected in a red-cedar chest from June of one year to May of the following year, and then to transform normally to the adult stage. The older larvæ of carpet beetles can be removed from clothing before it is stored in chests by thorough brushing. It is valuable to know that red-cedar chests will kill the very young larvæ. It should always be remembered that articles such as balls of yarn, floor skins backed with woolen cloth, pillows stuffed with hair or feathers, and similar objects in the interior of which the older carpet-beetle larvæ can hide should not be placed in cedar chests until fumigated to kill the larvæ hidden where they can not be reached by brushing.
[11] Juniperus virginiana.
[12] Attagenus piceus.