ROSS: HOW TO COLLECT AND PRESERVE IXSECTS 7 



tice will prevent damage to the insects that might otherwise be 

 banged around in the net with a large amount of debris. 



Killing Bottles 



Construction. — The best killing bottles are made with potas- 

 sium cyanide, sodium cyanide, or calcium cyanide. These com- 

 pounds give a concentration of deadly fumes sufficient to kill 

 most insects in a very short time, which is desirable. Generally, 

 two sizes of bottles are used, and in either of them one of these 

 cyanides may give good results. Potassium cyanide and calcium 

 cyanide are the most convenient to handle. Only a small supply 

 should be purchased at a time, as they deteriorate rapidly. 



A pyrex glass test tube or strong ring-necked vial, about 

 three-quarters inch wide and 4 to 6 inches long, makes a good 

 cyanide bottle of the smaller size, fig. 3. Put about three-quarters 

 inch of granular potassium cyanide or calcium cyanide flakes 

 in the tube or vial. Cover with a tight plug of cellucotton, on 

 top of which put one or two loose plugs. Sodium cyanide is not 

 recommended for small bottles, as it comes in rock form and 

 is difficult to handle. Instead of cellucotton, you may use saw- 

 dust and a plaster of Paris batter. In the latter case, cover the 

 cyanide with one-quarter inch of sawdust and over it pour one- 

 quarter inch of newly mixed, thick batter of plaster of Paris and 

 water. Allow the batter to harden for a few hours; then keep 

 the bottle tightly corked. 



The larger cyanide bottle, fig. 3, which should be sturdy, 

 may range in capacity from one-half pint to a quart. In the 

 larger bottle, the cyanide should always have the plaster of Paris 

 covering. The layer of sawdust and plaster should be a little 

 thicker than that for the smaller bottle. Rock sodium cyanide 

 may be used in the larger bottle if more convenient than calcium 

 cyanide or potassium cyanide. 



Label all killing bottles and other containers of cyanide con- 

 spicuously with the word POISON ; keep them tightly corked and 

 away from children or adults who do not realize the extreme 

 deadliness of the compounds. Never test the strength of a killing 

 bottle by taking the cork out and smelling the contents. As an 

 added precaution and safeguard to the collector, tape the bottom 

 of the cyanide bottle to protect it against breakage. 



The bottle should be almost entirely filled w T ith loosely 

 crumpled, soft paper, which should be changed whenever it gets 



