COLLECTING AND PRESERVING INSECTS BANKS. 



51 



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in the bottom of the bottle, covering it with a little dry plaster of 

 Paris; then mix some plaster of Paris with water, just sufficient so 

 that it is about as thick as can be stirred; then pour it over the 

 cyanide so as to cover it to a depth of about 5 mm. (one-fourth 

 inch). The bottle is then left open for a couple of hours until the 

 plaster is dry. After this the bottle should always be kept corked, 

 so that the fumes of the cyanide are strong enough to kill the insects 

 in a few moments. It is always well to place a few strips of blotting 

 paper in the bottle to absorb any moisture and to prevent the insects 

 from shaking against one another. A bottle well 

 made should last several years. 



Great care should be exercised in handling potas- 

 sium cyanide, as it is a deadly poison, and if any 

 is left over after one has prepared all the bottles 

 desired it should be buried deeply in the ground.. 

 For small tubes a lump of cyanide may be 

 wrapped in paper till it fits tightly in the bottom 

 of the tube (fig. 93). Some prefer to fasten the 

 paper containing the cyanide to the inside of the 

 cork. In collecting a variety of insects one should 

 have at hand a number of cyanide bottles, some 

 large ones and others of a smaller size, so that 

 the insects of each size may be kept together. 

 Very delicate insects should be put in a cyanide 

 bottle with a great deal of paper and no larger 

 insects with them. Similarly, long-legged species 

 should be kept by themselves. 



Some claim that a few drops of tartaric acid 

 added to the cyanide will make a stronger poison. 

 In dry regions the cyanide does not act so 

 quickly, and a few drops of water, or tartaric acid, 

 or even soda water, will increase its effectiveness. 

 Others put sawdust over the lumps of cyanide 

 and then a layer of plaster of Paris. Mr. Rick- 

 secker advises putting the cyanide into a short 

 tube, closed up with blotting paper, and insert 

 the tube tightly in a hole through the stopper or cork of the jar, the 

 tube opening inside of the jar. By this method one can keep the jar 

 clean, washing it out when desired, and one can recharge the tube 

 easily, while the same stopper and charged tube can be used on 

 other bottles of the same size. Mr. Wenzel has used small tubes 

 open at each end, and charged in the middle with cyanide, for 

 collecting minute insects. 



Some entomologists for minute species, especially for securing 

 insects from an umbrella,- use a cork stopper through which is inserted 

 88552— Bull. 67—09 — -5 



IV 



m 



Fig. 93.— A focket cya- 

 nide TUBE. 



