PROBLEM 3 Hoiv Do We Try to Solve Our Insect 



Problems? 



In what ways are insects harmful to us? 



There are more than 600,000 species of 

 insects. A surprisingly large number of 

 them affect us directly or indirectly. 

 Some live as parasites on us and other 

 animals. Some of them carry disease 

 germs; they spread disease among do- 

 mestic animals as well as among men. 

 Some carry diseases such as blights and 

 wilts from plant to plant, causing great 

 losses in crops. 



Some insects attack trees in the forest, 

 along the roadside, or on city streets. 

 They may strip them clean of foliage or 

 destroy the wood or bark. The tree may 

 die slowdy or rapidly, depending on 

 where the insect settles and on what it 

 eats. The insects that attack trees prob- 

 ably cost us not less than 150 million dol- 

 lars every year in the United States alone. 



Some insects may destroy the wooden 

 framework of our houses, the carpets on 

 our floors, the paper on our walls, and 

 the clothes in our closets. The losses 

 caused in these ways are relatively small 

 yet far from unimportant. But the insects 

 that are of the greatest importance to us 

 are those that attack our crops: plants 

 standing in the field, and grains that have 

 been gathered and stored. 



We make an insect problem for our- 

 selves. When farms were only a few 



patches surrounded by forest or prairie, 

 insect damage was usually slight because 

 natural enemies kept the population 

 down. Now vast fields consisting of 

 many thousands of acres are planted to 

 a single crop. The nesting places of natu- 

 ral enemies are thus destroyed, and 

 harmful insects often increase alarm- 

 ingly. The history of the cotton boll 

 weevil is an illustration. In Mexico, 

 where cotton plants were raised in small 

 patches here and there, this insect re- 

 mained under control. But the southern 

 farmers of the United States planted 

 thousands of acres of their land to cot- 

 ton, and the boll weevil which had mi- 

 grated northward flourished and multi- 

 plied enormously. Each year more 

 cotton was planted and the boll weevil 

 pest grew worse. The large crops en- 

 abled the weevil to increase in number 

 rapidly. This was especially true because 

 its natural enemies were absent. Farmers 

 thus create a problem which must be 

 solved through ingenuity and at enor- 

 mous costs. 



Who suffers from the damage done b) 

 insects? Many species of insects do us 

 grave damage by injuring our crops. 

 The full extent of this damage is rarely 

 appreciated by people who live in cities. 

 And many city people fail to realize that 



