176 JOURNAL, BOMBAY NATURAL HISTORY SOCUETY.Vol. XV11J. 



sweep, a sharp turn of the wrist must be given (following a smart downward 

 or lateral stroke in order to bring the fly to the end of the net), in snch 

 a way that the end of the net containing the insect falls over the rim and so 

 makes a closed bag from which it cannot escape. The end of the net can 

 then be gathered up in the hand, and the fly forced into a still smaller space, 

 in which it will not be difficult to get it into a pill-box, and then to slip on the 

 lid. If the specimens are small, it is possible with care to get several into one 

 pill-box, Flies may also be transferred direct from the net; to the killing-bottle, 

 and so brought home dead ; but this method is not to be recommended, since 

 prolonged exposure to the effects of cyanide of potassium is apt to injure 

 the specimens; the ultimate condition of which, when so treated, is rarely as 

 satisfactory as if they had been brought home alive in pill-boxes. If, however, 

 it is necessary for any reason to dispense with pill-boxes, and to use the killing- 

 bottle in the open, a little crumpled tissue-paper should be placed inside it ; 

 this affords a lodgement for the specimens, and so lessens the risk of their being 

 injured by rolling about. 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. 



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 Diptera, such as 

 Tab anus, the pill-box may be opened without fear of the insect effecting its 

 escape ; after which a smart tap on the bottom of the box will cause the fly 

 to drop into the jar. Diptera should never be allowed to remain exposed to 

 the effects of the cyanide longer than is necessary to ensure their being quite 

 dead. If the poison is of reasonable strength, four or five minutes should be 

 sufficient to kill even the largest and strongest flies ; on the other hand, it 

 is necessary to make sure that the insects are really dead, since, if the expo- 

 sure to cyanide has been too short, flies will often appear to be dead when in 

 reality they are only stupefied. As soon as the insects are really dead, they 

 should be removed from the killiug-jar ; those in pill-boxes may be allowed 

 to remain therein until one is ready to pin thom, while the loose specimens 

 should be turned out on to a sheet of cork-carpet or pith. 



Methods of preserving Diptera other than by pinning. 



Diptera should away s be pinned, and this should be done as soon as they are 

 dead. If preserved in any other way, they will never make such satisfactory 

 specimens. 



