BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [66] 



tain Coleoptera, notably those of the Curculionid genus Lixus, are cov- 

 ered with a yellowish pruinosity resembling pollen, which is of an eva- 

 nescent nature, so that if the specimens are collected and killed by the 

 ordinary methods, the pruiuosity is completely lost. To preserve the 

 natural beauty of such species it is necessary to put each specimen 

 alive in a small vial and to kill it at once by means of a lighted match 

 held under the vial for a few seconds. In pinning or otherwise mount- 

 ing the specimen it should not be handled between the fingers. 



Many Hymenoptera and Lepidoptera, especially species with yellow 

 markings, if kept for any length of time in a cyanide bottle, will 

 become discolored, the yellow changing to reddish, and hence such 

 insects should not be left longer tharuiecessary in the bottle. If care 

 is exercised in this respect, no danger of discoloration need ordinarily 

 be feared. The chloroform collecting bottle may be used with these 

 insects if discoloration is- anticipated. All the more delicate insects, 

 including Hymeuoptera, Diptera, the smaller Lepidoptera, and the 

 Neuroptera, require special care in killing. Large numbers should not 

 be thrown into a killing bottle together, and plenty of bibulous paper 

 should be kept in the bottle to prevent moisture from accumulating 

 and wetting and ruining the specimens. It is frequently advisable to 

 pin Diptera, especially the hairy forms (as the Bee-flies), in the net and 

 transfer them at once to a cigar box containing a sponge moistened 

 with chloroform. When the collecting shears are used, the insects are 

 always thus pinned at once, which is, in fact, the only method of 

 securing them. This is also necessary in the case of many Lepidoptera. 

 Delicate Neuroptera maybe killed by the use of the cyanide bottle, or, 

 preferably, placed at once in a vial of alcohol, as these insects, in many 

 instances, cannot be kept securely if pinned or mounted. Large Lepi- 

 doptera, as the Bombycids, may be killed by pouring benzine, naphtha, 

 or chloroform over the thorax and abdomen. These substances evapo- 

 rate rapidly and do not appreciably injure the vestiture of the insects. 

 Some collectors, in the case of butterflies, seize them dexterously 

 between the thumb and finger, and give a sharp pinch on the sides of 

 the thorax. This will prevent the fluttering of the insect when trans- 

 ferred to the cyanide bottle, and, if carefully done, the scales need not 

 be rubbed off. It is objectionable, however, because the thorax is dis- 

 torted and subsequent anatomical study interfered with, and, in the 

 case of moths, should never be practiced, as the thorax affords import- 

 ant characters used in classification. Orthoptera maybe killed by the 

 use of the cyanide bottle but should be transferred at once to the vials 

 of alcohol. If placed in a cyanide bottle, especially in the case of 

 Locusts (Acridida'}. they are apt to exude colored juices from the mouth, 

 so that the specimens become soiled. Hence the use of vials of alcohol 

 is preferable, ;ind these insects should never be thrown into vials con- 

 taining delicate insects of other orders. Plant-lice, together with the 

 plant which they infest, should be placed at once in vials of alcohol, 



