CONSIDERATIONS FROM STUDY OF INSECTS 261 



as carried by the tsetse fly. Several other diseases of man and 

 many other animals, especially cattle, are carried by flies. Tho 

 Texas fever of cattle is carried by a cattle tick, an animal closely 

 allied to the insects. 



When flies are plentifiil, there is a considerable increase in the number of cases 

 of illness among babies. 



Economic Loss from Insects. — The money value of crops, 

 forest trees, stored foods, and other material destroyed armuallj' 

 by insects is beyond belief. It is estimated that they get one tenth 

 of the country's crops, at the lowest estimate a matter of some 

 $300,000,000 yearly. 



" A recent estimate by experts put the yearly loss from forest insect 

 depredations at not less than $100,000,000. The common schools of 

 the country cost in 1902 the sum of $235,000,000, and all higher institu- 

 tions of learning cost less than $50,000,000, making the total cost of edu- 

 cation in the United States considerably less than the farmers lost from 

 insect ravages. 



" Fm-thermore, the yearly losses from insect ravages aggregate nearly 

 twice as much as it costs to maintain our army and navy ; more than 

 twice the loss by fire ; twice the capital invested in manufacturing agri- 

 cultural implements ; and nearly three times the estimated value of the 

 products of all the fruit orchards, vineyards, and small fruit farms in the 

 country." — Slingerland. 



In 1874-1876 the damage to crops by the Rocky Mountain 

 locust has been estimated at $200,000,000. At certain times, these 

 locusts migrate from Colorado, Wyoming, and Dakota, where they 

 seem always to be found, and descend in countless millions upon the 

 grain fields to the eastward. Fortunately, these invasions ha\'e 

 been rare in recent years. The total value of all farm and forest 



