438 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1962 



The chinch bug is a good example. The corn belt was originally a 

 gi-assland with an Andropogon Climax vegetation. This was the 

 native food plant of the chinch bug which sucked the juices of the 

 grass and hibernated in the adult stage m the clmnps of dead grass at 

 the base. Man decided he could raise the finest corn and wheat here. 

 He plows out the Andropogon and plants two crops which he fertilizes 

 and cultivates, causing them to grow rapidly, to be succulent and 

 higlily attractive to insects, and these two crops fit perfectly into the 

 two seasonal generations of the chinch bug, spring on wheat, summer 

 on corn ; and then he wonders why these enormous populations destroy 

 his crops. 



In like manner man changes the course of streams, impounds water, 

 constructs artificial barriers, and in general changes natural condi- 

 tions, and in so domg he destroys the original balance. 



THE STRUGGLE FOR DOMINANCE 



Wlien we view man as a competitor in the insect world, attempting 

 to subdue his invertebrate rivals, we must face up to certain facts and 

 considerations. The insect is an animal without intelligence, or at 

 least the ability to think, which has come to its present position of 

 dominance in the world by mutation, selection, and adaptation. As 

 pomted out, it is higlily adapted to most conditions in the world. 



If there is any doubt concerning its ability to overcome anything 

 adverse which is devised for its destiiiction, we have only to look upon 

 the chemical developments and history of the past two decades. Man 

 has devised the most deadly chemicals he could fijid in the clilorinated 

 hydrocarbons and organic phosphates which at first seemed to wipe 

 out completely populations of house flies, roaches, body lice, and most 

 agricultural insects for months at a time. In 5 to 10 years time these 

 chemicals have proved ineffective on the descendants of these 

 same insects. 



When D.D.T. was first used, a prominent biologist stated that the 

 house-fly problem was forever solved. In 5 years from that date, we 

 were rearing them m our laboratories in screen cages which were white 

 with coatings of D.D.T. painted on the wire screen. Wliere does man 

 hope to go in his fight with selective adaptation or tolerance of this 

 type? 



Man, on the other hand, is an intelligent animal with the ability to 

 think, and his choice of adaptation has been in this direction. In 

 man we visualize another type of biologic experiment in the world. 

 We see the development of an entirely different type of animal body 

 with a different type of appendage, the hands. With these he makes 

 tools with which to make gadgets and devices for obtaining materials 

 and directing the forces of the earth, thus converting or changing the 



