COLLECTING ECONOMIC PLANT DATA 51 



quito netting over a wooden frame. The cage should have a hinged door 

 and a solid floor to hold dirt. 



Material for the identification and study of an insect pest should be 

 generous in quantity, especially if the insect is new or little-known, 

 and should include both adult and various immature forms. 



A collector's net will be necessary to catch butterflies, moths, flies, 

 and some beetles. 



Killing 



Insect specimens can be killed by chemical fumes (in a killing bottle), 

 or by immersing them in 75-percent alcohol, but neither method is 

 suitable for all types of insects. Most collectors use cyanide for killing 

 bottles. These can be made from any sort of a glass jar or bottle having 

 a wide mouth and a tight-fitting lid or stopper. The glass should be 

 thick enough to lessen danger of breakage. Either potassium cyanide 

 or sodium cyanide may be employed, but both are deadly poisonous to 

 all kinds of animals and should be handled with extreme caution. 

 Several small lumps of the cyanide, wrapped in pieces of thin paper, 

 are placed in the bottom of the bottle and then wadded down firmly by 

 placing a circle of blotting paper on top. A layer of plaster of paris can 

 be used to fix the poison in the bottom of the bottle. A cyanide killing 

 bottle will last several years if properly prepared and used. Killing 

 bottles can be made also by moistening wadded paper in the bottom 

 of the bottle with carbon tetrachloride, ether, or chloroform, but this 

 type of killing bottle needs to be recharged with the fluid at the begin- 

 ning of each collecting trip. 



If extensive collecting is contemplated, a number of killing bottles of 

 various sizes will be needed, because it is never a good idea to mix many 

 kinds of insects together in a single bottle. Each collection should be 

 removed as soon as dead and kept separate in pill boxes or other small 

 containers. For pickling in alcohol, a quantity of small vials and bot- 

 tles of assorted sizes will be required. 



Preserving 



The killing-bottle method is best for adult stages of butterflies, moths, 

 flies, grasshoppers, and true bugs. The last named can be kept in 70- 

 to 75-percent alcohol, which serves also for beetles, ants, aphids, leaf- 

 hoppers, and for all the immature stages of any insect. Caterpillars, and 

 any of the larger larvae, will preserve best if killed b}^ boiling in water for 

 1 to 5 minutes before transferring to the alcohol. The best preservative for 

 thrips consists of 8 parts of 95-percent alcohol, 5 parts distilled water, 1 

 part glycerine, and 1 part glacial acetic acid. Collections of scale insects 

 can be made by cutting off sections of the plant tissue with the scales 

 attached and allowing all to dry completely. 



Any specimen not preserved in liquid will need a thorough prelimi- 

 nary drying in the sun, or by artificial heat, before being stored or shipped. 

 This is especially true for large specimens; otherwise they will be dam- 

 aged by molds. Insects from the killing bottle need to be packed into 

 final containers before drying; otherwise undue handling or shaking 

 about will break off the legs and other appendages. Butterflies and moths 

 are placed in individual paper triangles folded to fit the specimen. Loose 

 specimens can be put into small boxes carefully packed with soft paper, 

 or cellucotton, if this is available. Ordinary cotton should not be used 

 for this purpose. Small paper cylinders are quite satisfactory as substi- 



