NO. 13 STAPHYLINIDAE BLACKWELDER 5 



Three general means of mounting and preservation have been em- 

 ployed Ijy entomologists. These are: On pins, in fluid such as alcohol, 

 and on microscope slides. According to Chamberlin (1931) : 



It may be said that the important thing in the preparation of material for 

 study is not the following of any particular set method, but rather the treatment 

 of material in such a way that the structures which it is necessary to employ 

 in systematic work (that is, those structures, regardless of size or obscurity, 

 which the study of comparative morphology shows to be significant for such 

 purposes) shall be rendered clearly visible. 



In no group of insects will either of the first two methods alone 

 suffice to this end, and in all of the groups of minute insects the slide 

 preparations, supplemented in certain cases by the other methods, 

 have unquestionably proved to give not merely better results but the 

 only reasonably complete and satisfactory ones. 



The Staphylinidae may properly be regarded as a group of minute 

 insects, as only a comparatively small percentage of them exceed 8 mm 

 in length, and the average length is probably below 5 mm. The actual 

 size ranges from slightly over 5 cm down to less than i mm. 



The usual methods of mounting small beetles on pins and paper 

 points permit an examination of only the larger and more obvious 

 characters, and is utterly useless in any detailed study of the mor- 

 phology. It is essential in this type of work that the separate elements 

 of the body wall be carefully dissected and perhaps examined with 

 transmitted light, and this requires a considerable preparation of the 

 material. 



The method of preparation worked out for the present study is 

 outlined below. It is a modification of the practice generally employed 

 in the study of minute insects such as scale insects and lice. 



Because of the methods used in the past in the examination and 

 description of species and the establishment of classifications, it is 

 impossible to correlate with the literature identifications in the Staphy- 

 linidae made from slide preparations. For this reason specimens 

 should first be mounted on fine paper points on pins in the usual 

 manner and identified as accurately as possible using all available aids. 



The special technique is as follows : The specimen is dropped into 

 a 10 percent solution of KOH and heated to near the boiling point 

 for about half a minute. This is to soften the body sufficiently to 

 prevent breakage when the elytra and wings are dissected ofif, which 

 is done by removing the specimen to water in a watch glass and work- 

 ing under the binocular microscope with fine dissecting needles. The 

 abdomen is now dissected away behind the metasternum, the head 

 separated from the prothorax, and the prothorax from the remainder 



