INSECTS 239 



* 



may be killed by placing them in poison bottles for a few 

 hours. These bottles should have wide mouths and good 

 corks. A piece of cyanide of potassium, which is such a 

 deadly poison that even breathing its fumes will kill insects 

 and other animals, may be fastened in the bottle by pouring 

 over it some wet plaster-of-Paris. A piece of the poison as 

 large as a hickory-nut is enough for a four-ounce bottle. Let 

 the plaster dry and then cork up the bottle. After insects 

 have been killed they may be pinned into a cigar box, in the 

 bottom of which has been fastened a sheet of thick corru- 



FIG. 138. : A caterpillar-hunting ground beetle and its larva. (From Smith's 

 "Insect Friends and Enemies.") 



gated paste-board. A good way of preserving large butter- 

 flies, moths, and other large insects is shown in Fig. 124 B. 

 Beneficial Insects. Not all insects are harmful. There 

 are indeed a great many groups that are beneficial in one way 

 or another. The silk worm produces a product worth many 

 millions of dollars annually in the commerce of the world. 

 Honey bees store large quantities of honey used as human 

 food, and also carry pollen from blossom to blossom, thus 

 increasing the crops of fruit. The ground beetle (Fig. 138), 

 tiger beetle, and some other insects prey upon other injurious 

 insects and thus act as a balance in Nature's forces for the 

 control of the enemies of man. The spotted lady-beetle (Fig. 

 139) destroys many thousands of the San Jose scale insects. 



