Tropical Fruit-Fly Menace 



By L. D. Christenson 



Entomology Research Division, U.S. Department of Agriculture 



[With 6 plates] 



Insects occur in almost endless variety. More species exist — some 

 800,000 have been described — than all other kinds of animals put 

 together. 



Insects can breed so rapidly that they would soon overrun the 

 earth if uninhibited. They are among the strongest of man's com- 

 petitors for food for his table, for animal and plant fibers to make 

 his clothes, for lumber to build his shelters, for flowers that grace his 

 table, sometimes even for the game he seeks in field and forest. Dis- 

 eases spread by insects kill or make seriously ill millions of people 

 each year. 



Our six-legged rivals consume vast quantities of food so desperately 

 needed by hungry people in many parts of the world. Some years 

 ago Dr. L. O. Howard, eminent pioneer in the science of entomology, 

 stated : "There is a third way of assisting in the feeding of the world 

 aside from birth-control or the stimulation of plant food or the inven- 

 tion of new food, and that is the stopping of waste. Probably the 

 greatest of these wastes is the tremendous but unnecessary tribute 

 that we pay to insects." Despite important advances in insect control 

 in the years since Dr. Howard arrived at these conclusions, there is 

 still truth in them today. If we did nothing about msects, our agri- 

 culture would revert to an uncertain gamble because of frequent insect 

 plagues. In modern times insects cause damage to crops, livestock, 

 forests, fabrics, houses and other buildings amounting to nearly $4 

 billion each year in the United States alone. 



Among the most noxious, and at the same time most interesting, 

 insect families are the so-called tropical f niit flies, family Tephritidae. 

 This is a large family comprising some 4,000 species distributed 

 throughout the world. The wings and bodies of many are beautifully 

 adorned with yellow, brown, or black markings. Some fruit flies 

 attack the ovaries and seeds of plants ; others lay their eggs in fruits 

 and vegetables. Most are strong fliers. The Mexican fruit fly (^7i«5- 



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