METHODS OF COLLECTING AND PRESERVING DROSOPHILIN^. 47 



on which the specimen was found, etc.) should be placed on a separate 

 label. 



It is often not convenient to mount specimens as they are collected. 

 I have found the following method very satisfactory for keeping 

 material until it is mounted: A paper tube is made, by wrapping a 

 small piece of paper around a pencil and bending in one end so it 

 will stay closed. This is then filled with specimens, which are shaken 

 down (before they become thoroughly dry and brittle), until they do 

 not rattle around. Such a tube, with the upper end folded in so as 

 to stay shut, and properly labeled, may be kept indefinitely so long 

 as it is kept free from mold, dermestids, and ants. It will also stand a 

 surprising amount of rough treatment, provided the specimens are not 

 too loosely packed. When one is ready to mount the specimens he 

 has only to place the tube in a moist chamber for a day or two. Then 

 when it is unrolled the specimens will be relaxed and ready for mounting. 



A collection of small Diptera is not as difficult to keep up as is a 

 collection of larger insects, for the reason that dermestids do not 

 very often attack such small forms. One must, however, keep such 

 specimens in tight wooden boxes, and moth-balls should be kept in 

 the boxes. If ordinary pins be heated red hot and their heads stuck 

 into moth-balls, the latter may then be readily stuck in the insect 

 boxes. If a collection does become infested, a liberal dose of carbon- 

 bisulphide fumes will remove the difficulty. 



A microscope is necessary for the study and identification of most 

 Drosophilinae. A binocular will be found most convenient. When 

 examining pinned specimens two flat pieces of cork fastened together 

 at a right angle will be found very useful, as they will enable one to 

 examine the specimen from any angle, and yet have it held steady. 



Reflected light should ordinarily be used ; but for the details of wing- 

 venation transmitted light is sometimes necessary. 



