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(5) Whenever possible, chemicals should be applied at the seasons of the 

 year when wildlife damage will be least. Some applications of pesticides can be 

 made during the winter season when fewer birds are present in most northern 

 areas than during the spring migration period; also, certain birds are rela- 

 tively more mobile during the winter season. 



(6) Conscientious effort should be made to be sure that pesticides are 

 applied at no more than the intended rates and that no areas receive double 

 doses. 



Although these procedures will help to minimize damage they are not 

 entirely satisfactory for the protection of wildlife [ll]. 



More attention should be given to developing chemicals specifically toxic 

 to only one particular group of animals. For example, in control of the lamprey 

 in the Great Lakes, the Service screened thousands of compounds to obtain one 

 or two that were fairly specific for lamprey larvae. 



Biological methods of control also should have more study. Suppression 

 of insects by other insects and by disease is a very important factor in regu- 

 lation of insect numbers, despite all the use of pesticides [l9], (Lilly, 

 unpubl.). An unusual example of effective biological control was the result of 

 research by the U. S. Department of Agriculture. Screw worms were controlled 

 by releasing irradiated, sterile males, which in turn led to infertile eggs 

 being laid by the females and thus reduced the population. Probably other in- 

 sects could be controlled by biological means at least to a degree. Biological 

 methods supplemented by judicious chemical control probably could control some 

 insect pests more inexpensively than by chemicals alone. 



Other promising control methods include planting and harvesting at par- 

 ticular times; proper fertilization and rotation of crops; destruction of 

 insect wintering quarters; and manipulation of water levels. 



Certain research entomologists who work with economic pests believe the 

 development of varieties of plants and animals that are resistant to trouble- 

 some insects and disease holds the greatest promise of all from the long-time 

 standpoint. 



