CHAPTER XXIII 



THE GRASSHOPPER 



WE have seen from our study of the crayfish that it was an arthro- 

 pod— 1 that is, had hollow jointed feet, and that the phylum 

 arthropoda is often divided for convenience into branchiata — 

 (gill-breathing) and tracheata (breathing by air tubes). 



The two tracheata most commonly studied in the laboratory are the 

 bee and the grasshopper in this country, and the cockroach in England. 

 Each of these organisms well represents the group to which it belongs. 

 The bee is the more highly specialized, and many books have been writ- 

 ten about this interesting animal; in fact, so much so that the subject- 

 matter covering it is almost inexhaustible. The grasshopper, however, 

 because it is considerably larger than the bee, is preferred by many 

 teachers. 



The study of this animal is representative of the greater part of the 

 animal kingdom, for this is an insect, and there are more different kinds 

 of insects than there are of all other animals put together. 



IMPORTANCE OF INSECT PESTS 



Some of our most important garden pests are insects, and it has 

 been estimated by competent authorities, that one-tenth of all farm 

 products are destroyed by such pests. Now, there are very few of us 

 who would not object to being obliged to pay one-tenth of all we earned 

 to anyone for the privilege of working. Still, how low our average in- 

 telligence is, may be noted from the fact, that while a loss of one-tenth 

 of all our food is constant, year in and year out, the average farmer 

 would object very strenuously to paying out even one-tenth of the tenth 

 he loses to pay the salary of a group of trained men to prevent this loss 

 from occurring. And this is true, even though he would thus be in- 

 creasing his income to a considerable extent. 



Let us illustrate by actual figures. The average farmer, let us say, 

 has an income from all his crops (and this income, of course, includes 

 his living expenses, as he raises the greater portion of his food) at the 

 lowest estimate, of about $2,000 each year. He should have, if the insect 

 pest were controlled, $2,200. Yet, if he were asked to contribute $20 

 each year to such control he would rebel. But as each and every one of 

 us must live on what the farmer produces, we must pay $2,200 for $2,000 

 worth of food. That is, we must pay $100 a year extra for every thou- 

 sand dollars we spend for food. 



Let us consider the item of clothes. These may be of cotton, wool, 

 or silk. Cotton and wool are farm products, and so also is silk. The 

 silk grower also must have this extra $100 to pay his own expenses 



