DIPTEBA (TWO- WINGED FLIES). 
69 
about. It may be noted that Anthracinse when placed in pill-boxes 
are very apt to injure their wings by buzzing about ; large Tabanidce, 
^Estridce, and certain other Diptera are liable to suffer in the 
same way. On the other hand, the hairy and scaly body-covering 
of these species is very easily rubbed off, so that if carried in the 
killing-bottle they must be treated with especial care. It is always 
advisable when out collecting to carry a killing-bottle for use 
in case of need, in the event of the supply of pill-boxes running 
short. Diptera on windows may be captured in pill-boxes ; if the 
edge of the box is slightly raised from the glass on one side, and 
a little tobacco smoke blown into it so as temporarily to stupefy 
the fly, it will be found easy to slip on the lid without allowing the 
insect to escape. 
Spieit not to be Used. 
Unless intended for dissection, Diptera must on no account be 
placed in spirit. Since all descriptions of Diptera have been based 
upon dried specimens, flies in spirit have to be taken out, dried, and 
pinned before they can be examined and compared with descriptions. 
In drying, however, they invariably shrivel ; while immersion in 
spirit often causes colour-markings to disappear, and inevitably 
results in hairs, scales, etc., being washed off or matted. Specimens 
intended for dissection (as when it is desired to examine some specially 
remarkable structure, such as the proboscis or genitalia) should, 
however, always be placed in a small tube of spirit, with a plug of 
cotton-wool on the top of them to prevent their being injured by 
washing about. Other specimens of the same species should be 
pinned and labelled with a reference to those in spirit, so that the 
latter may be identified. 
Killing. 
Diptera brought back alive after a day's collecting should be killed 
by being placed for a few minutes in the closed cyanide-bottle or jar. 
If the cyanide-jar is sufficiently large, the pill-boxes themselves may 
be placed therein, first opening them a fraction of an inch on one 
side to allow the cyanide to take effect. In the case of large sluggish 
