Precaution Against Pests
Certain insects, such as flour beetles and carpet beetles, feed upon dried insects, and unless precautions are taken these may entirely destroy a collection. To guard against them, various chemical repellents may be placed in the boxes containing specimens. Naphthalene, of which ordinary mothballs are composed, is one of the best repellents. A few mothballs may be put in a cloth bag pinned securely in one corner of the box, or the heads of common pins may be inserted into naphthalene mothballs, and the points stuck in the corners of the box, [fig. 17].
Naphthalene is chiefly repellent in action; its odor keeps out pests, but, if they are already in the specimen boxes, naphthalene will usually not kill these pests, and some other substance must be used.
Paradichlorobenzene, called PDB, is a good fumigant to use on pests in the collection. It should be used in a nearly airtight container, such as a tight trunk, bin, or case, at the rate of 1 pound of PDB to 25 cubic feet of space. The boxes of specimens, with lids open or removed, should be placed in the container, the fumigant scattered or spread on a piece of cloth or paper above them, and the container sealed for about a week.
Fig. 17.—A naphthalene mothball mounted on a common pin. It serves as a repellent to keep away from the collection live insects that might cause damage. To insert the pin, stick the point in a cork, heat the head in a flame, and then push the head into a mothball. The pin will melt its way into the naphthalene, which will cool and harden again almost immediately.