COLLECTING AND PRESERVING INSECTS BANKS. 



95 



long trial glycerin mounts have proved very unsatisfactory, even 

 when carefully mounted and ringed with a supposedly impervious 

 cement. 



Diaspine scales. — Diaspine scales are boiled in caustic potash, the 

 method of boiling varying from a few seconds to half a minute 1 for the 

 very strongly chitinized species. Specimens thus softened and par- 

 tially cleared are transferred 

 from the tube directly to a 

 microscope slide and care- 

 fully washed with warm 

 water with the aid of a 

 pipette. Washings with 95 

 per cent alcohol follow, and 

 the scales are then floated 

 to the center of the slide 

 and arranged in a line, with 

 the pygidia pointing in one 

 direction; after which the 



alcohol IS removed With fig. 147.— One of the Fulgorid.e, Poiocera fuliginosa. 



bibulous paper. Before the 



alcohol is entirely evaporated a small drop of oil of cloves is applied 

 and slightly heated to drive off the bubbles of air and to cause the 

 oil of cloves to penetrate the specimens. The oil of cloves having 

 been removed, a very small drop of balsam is added and a clean 

 cover glass is applied and held in place with a steel clip while the 

 slide is heated for a few seconds over an alcohol lamp to dry the 

 balsam. If care is used, the balsam can be quickly dried, so that 

 upon cooling it is perfectly hard. Fifteen to twenty 

 minutes are ordinarily needed for such preparation. 

 Xondiaspine scales. — In mounting the soft-bodied 

 scales various methods are necessary for clearing 

 the insects on account of the remarkably diverse 

 coverings which the\ r produce. With the lac insects 

 and species of the genus Ceroplastes it is often 

 necessary to boil the specimens in chloroform or 

 acetic acid to remove the wax. Mealv-bugs and 

 Lecaniums can be immediately removed to the 

 potassium hydroxide and boiled similarly to the 

 diaspine scales. However, it is frequently neces- 

 sary to boil the specimens for a long period, and 

 also to prick holes through the body w r all to allow the escape 

 of the body contents. After boiling, the specimens are washed 

 in warm water, and dehydrated with two or three grades of 

 alcohol, then arranged upon a slide, and clove oil or xylol applied 

 preparatory to mounting in the usual way in Canada balsam In 

 mounting very convex species it is frequently necessary to slit the 



Fig. 148.— One of the 

 psyixiixe, psylla 

 pyeicola. 



