COLLECTING DIPTERA. 285 



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of blotting-paper is then coiled within this cavity, and it 

 is over this that a few drops of a solution of cyanide of 

 potash is poured/ 3 * 



It is useless to collect flies in a bare bottle; the insects 

 soon exhale moisture sufficient to ruin them. The blotting- 

 paper prevents this, and the cork can readily be removed 

 from one bottle and put into another when a sufficient 

 quantity of flies is collected.! Moisture of any kind in- 

 jures flies. 



(( - In the earlier part of the season many rare specimens 

 of Diptera may be obtained by beating. For this purpose 

 I employ a rather heavier net -wire, to which a pointed net 

 of cheese-cloth is attached. On such occasions it is neces- 

 sary to carry with one a larger bottle with a little cotton- 

 wool in the bottom for chloroform, and a vial of the latter 

 in the pocket to -be poured into the larger bottle. By 

 thrusting the end of the net, with its contents, for a few 

 seconds into the chloroform bottle, one can then remove 

 the specimens undisturbed. Mik advises that minute flies 

 should be preserved alive in small bottles filled with paper 

 clippings, through the cork of which a small glass tube is 

 thrust nearly to the bottle. For a collecting-net, after 

 many experiments and failures, I have found most service- 

 able a simple, rather light, brass wire, soldered together to 

 form a ring about 28 cm. (10-11 inches) in diameter, and 

 firmly attached to a light handle about one metre long. 

 The net is made of very coarse bobbinet lace, the most ser- 

 viceable and, in the end, the cheapest material. The net 

 should be readily handled with one hand. 



" Specimens should not be allowed to remain overnight 

 unpinned. The large specimens may be pinned through 



* Dr. Williston writes me: "I notice that a good many collectors 

 now use such a bottle for all kinds of insects." 



f "If one," says Dr. Williston in a letter, " is so situated that he 

 cannot carry a box to pin specimens in, he should put cotton-wool or 

 paper clippings (rice paper) in his cyanide bottle to prevent the shak- 

 ing about of pilose specimens." 



