OUR FRIENDS THE INSECTS 



By W. V. Balduf 

 University of Illinois 



There is necessaril57^ such a preponderance of emphasis on the 

 losses man sustains through insects that a statement of the credit the 

 hexapods are responsible for is occasionally desirable to maintain a 

 correct mental perspective in regard to their relation with man's 

 welfare. It is a common and logical principle in educational psy- 

 chology that instead of setting up a long series of " don'ts " to regu- 

 late childrens' conduct we aim to substitute legitimate and desirable 

 activities for those we would prohibit. In a somewhat parallel man- 

 ner much has been done, and much more may perhaps be accom- 

 plished in the future, toward subduing injurious insects by estab- 

 lishing beneficial forms among the undesirable species. Instead of 

 creating a partial biological vacuum in nature by killing insects by 

 artificial methods, we may plant a benefactor where a criminal rules, 

 lest the house that is sw^ept clean and vacated be eventually filled 

 with seven times more devils than at first. Obviously this plan has 

 limitations inasmuch as effective checks do not exist for all pests. 



BIOLOGICAL CONTROL 



The method of combatting insect pests by the utilization of natural 

 agencies that hold the destructive forms in check is, perhaps, the most 

 fascinating chapter in the history of insect control and at once the 

 least known by the people as a whole. The present attempt is only 

 to prepare a brief, simple account of the growth, methods, and ac- 

 complishments of this phase of warfare against insects. The sub- 

 ject stated comprehends other phases of entomology than this, but 

 the present article will be limited to a consideration of our friends, 

 the parasitic insects. The term " parasitic " as used here is defined 

 to include only such insects as live upon other insects, spending a 

 whole stage or more on or in another individual which is designated 

 the host. 



1 Reprinted by permission from the Transactions of the Illinois State Academy of 

 Science, February, 1929. 



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