INSECTS 



403 



The insects are among the most important of animals. 

 This class contains more than half the known animal species. 

 They are spread widely over all parts of the earth. 



Both good and bad insects abound. Economically, they 

 furnish millions upon millions of dollars' worth of produce 

 every year and on the other hand destroy hundreds of 

 millions of dollars' worth of crops and trees. It has been 

 estimated that in the United States insects destroy every 

 year crops and trees which have a 

 value of $50,000,000, to say nothing 

 of the countless losses due to dis- 

 eases spread by flies and mosquitoes. 

 (Page 452.) Not many years ago 

 grasshoppers nearly devastated sev- 

 eral of the middle western states. 



The most productive insects are 

 the silkworms and the bees. With- 

 out the silkworm (Figure 131) there 

 would be no silk produced, and with- 

 out the bee, no honey. These two 

 products each year run into hundreds 



of millions of dollars. We have already seen that bees and 

 other insects are needed also for the fertilization of flowers. 



Among the most interesting of the insects and perhaps, 

 everything considered, the most valuable, is the honey-bee. 

 This is the great flower fertilizer ; it would fertilize about all 

 the plants man really needs except the red clover. In the 

 United States alone there is produced by it about twenty- 

 five million dollars' worth of honey and wax each year. 



In Experiment 133, it was found that the body of the 

 bee, like other insects, is divided into three parts. These 

 parts are called head, thorax, and abdomen. The eyes 



FIGURE 131 



