1921 ENTOMOLOGICAL SOCIETY. 45 



investigations and field experience — both are important — develop a fund of infor- 

 mation sufficient to ensure a satisfactory disposal of the case. The bean lady- 

 bird situation in Alabama with no Federal or State funds available is a striking 

 instance of unpreparedness. An incipient infestation compels immediate, though 

 somewhat wasteful, action if an insect is to be eradicated. Time, tide and insects 

 wait for no man. The drastic and prompt extermination of the Colorado beetle 

 infestations in both England and Germany are cases of this character. 



The utilization of natural enemies of one kind or another for the control of 

 insects should be advocated wherever practicable. There is no question as to the 

 great value of many birds in checking leaf-eating caterpillars and the better 

 protection of bird life is one of the most promising methods of safeguarding 

 forest areas from insect depredations. 



The importation of the Australian lady beetle and its speedy control of the 

 cottony cushion scale gave a great impetus to the utilization of natural enemies. 

 The collection and redistribution of native hibernating lady beetles on the Pacific 

 slope is a similar method of making use of beneficial insects. 



Most of our recently introduced pests are comparatively insignificant forma 

 in their native countries, and are there controlled presumably very largely by 

 beneficial insects. The extended and systematic introduction of natural enemies 

 of both the gypsy and brown tail moths has resulted in a very thorough study of 

 these insects and eventuated in a reasonable expectation of control through these 

 agencies. The present search for the natural enemies of the green Japanese 

 beetle and of the European corn borer are later attempts along the same line. 



There is also the possibility of utilizing native beneficial insects. Doctor 

 Pierce made an extensive study of the parasites of native weevils and has demon- 

 strated the possibility of concentrating them upon the introduced cotton boll 

 weevil. Similar work has been undertaken in connection with the European corn 

 borer. The probabilities are that native species will largely retain their charac- 

 teristics when attacking introduced forms as was the case with the extraordinary 

 abundance of Trichogramma in the eggs of the European corn borer in 1919, and 

 its relative great scarcity the past season. The possibilities along this line are 

 well worthy of most careful attention. 



The marked reduction in the numbers of a certain insect may have a much 

 greater effect than is commonly supposed. The studies of bark beetles by DoctoT 

 Hopkins have shown the possibility of securing very efficient control by simply 

 reducing their numbers, in some instance's by seventy-five per cent, to such an 

 extent that those remaining would be unable to overcome the resistance of the 

 tree. This of course applies to enemies of living trees and presupposes that a 

 minimum amount of injury must be inflicted or the attack can be successfully 

 resisted, a condition which accords very closely with the facts. 



The work of W. E. Fisk upon the Tsetse fly has shown that it is only necessary 

 to reduce the infestation by this pest to moderate limits in order to secure very 

 satisfactory freedom from attack. The studies of Eoubaud upon malaria in France 

 indicate intimate connection between this disease and the numbers of mosquitoes 

 per host. The author suggests what he calls animal prophylaxis, that is the 

 introduction of enough cattle to attract the insects and thus to protect man to 

 a large extent. Both of these cases are simply forms of percentage reduction. 



Somewhat similar conditions prevail when the fanner relies upon good cul- 

 ture to prevent insect injury, since vigorous growth frequently enables the plant 



