32 



INTRODUCTION. 



must always be left sufficient space below the insect for at least 

 two or, perhaps, three labels, and room again after that for the 

 forceps to grasp the pin.* 



In pinning small and very minute Diptera with the short, very 

 fine pins, they are best pinned when lying on the left side, the 

 pin passing through the thorax just below the dorsum, and at 

 such an inclined angle that it emerges trom the lower (left) side 

 just above the coxae. By thus piercing the thorax obliquely, it is 

 possible, by slanting the pin slightly when mounting it on pith or 



Fig. 6. Method of mounting (a) a moderate-sized fly, (b) a very small fly. 



cork, to enable the student to examine both the dorsum and the 

 right side of the insect without removing it from the cabinet. 

 These minute pins should carry the specimens as near their heads 

 as possible, and be stuck in neatly-cut, oblong pieces of white 

 pith or similarly shaped pieces of cork covered with white paper. 

 These pieces of pith should be broad and long enough to protect 

 the head and legs to a moderate extent, but no broader, otherwise 

 it is impossible to place a strong hand-lens near enough to examine 

 details. Moreover the pith should invariably be of some depth, as this 

 secures a tighter grasp of the large pin which must be thrust through 

 the end of the pith opposite that bearing the specimen.t A dot of 

 white gum placed on the upper side of the pith on the spot where 

 the small fine pin is inserted will fix it securely and a larger drop 

 of gum should be placed around the strong pin where it emerges 

 from the under side of the pith. Some collectors, however, 



* In removing a delicate specimen from the cabinet the forceps should 

 grasp the pin above the insect ; in replacing it, the forceps should grasp the 

 pin below the insect, thus in each case minimising the chances of accident. 



t When fixing the small pin in the pith the head of the insect must be 

 directed away from the strong pin, not facing it, as the latter method adds to 

 the difficulty of viewing the head parts. 



