PRESERVING INSECTS 



23 



that the former is not quite so deep and is grooved to fit over the tongue 

 of the latter. The bottom is'covered with a series of wooden blocks 

 8 mm (1 in.) thick. 12 of his unit blocks just fill a box. There are 

 various sizes adapted to different needs, the idea being to put all of one 

 species on a single block, thus avoiding the necessity of repinning speci- 

 mens in rearranging a case, as the blocks themselves can be moved. 

 Where this system is used, it is found advantageous to have some of the 

 larger blocks covered with cork. 



Museum pests. In spite of great care and apparently tight cases, 

 the enemies of an insect collection are liable to work into the boxes. As 

 a deterrent to the entrance of insect pests, 

 many entomologists use naphthaline in 

 some form. Naphthaline cones mounted 

 on pins are most convenient, but are 

 rather costly as they retail by dealers at 

 75 cents a hundred, specially when naph- 

 thaline balls can be obtained for less then 

 10 cents a hundred. These latter can be 

 mounted by thrusting with the aid of pliers 

 the heated head of a pin into the ball. After it has cooled the ball 

 will be firmly attached to the pin, which may then be stuck into the 

 cork lining of any case. 



The presence of museum pests is revealed by the particles of com- 

 minuted matter under the injured specimen. Infested cases should be 

 treated with carbon bisulfid, pouring in about a teaspoonful, closing the 



Fig.. 27 Naplitlialinc cone and ball 

 (original). 



Fig. 28 Pinning forceps (original). 



case and allowing it to remain from several hours to a day. This sub- 

 stance evaporates readily and does not injure the specimens. As its gas 

 is inflammable and explosive great care should be exercised to prevent 

 its vapor coming in contact with any source of fire, as a lamp, lighted 

 cigar, etc. 



Convenient accessories. When arranging insects in a case, a pair 

 of pinning forceps will be found a great convenience. The large nickel 

 plated dental forceps are the best, but are too expensive for many. 



