INSECTS INJURIOUS TO AGRICULTURE 415 



and it seems that one could hardly expect appreciable results before 

 four or five years. 



But what does this matter in any event? since we are trying to 

 obtain a result of indefinite duration which will bring about exemption 

 from the ruinous methods of destruction by insecticides and which 

 will mark the end of a public calamity menacing the trees of the 

 whole United States. 



General Considerations and Conclusions 



The exposition of facts we have presented in this memoir allows us 

 to take stock of the importance gained during these recent years by the 

 method of utilizing beneficial forms. It can not be denied that, prac- 

 tised in a judicious manner, it can render very great services, and the 

 initiative of governments which have been encouraging large experi- 

 ments destined to show its value, must be applauded. It would be bad 

 taste indeed to criticize those who have brought about a check, for it 

 is only by trying experiments that one can understand the conditions 

 which may prevent success, and far from implying failure under such 

 conditions, the experiments almost always teach a useful lesson. 



Those accustomed to the experimental method and to laboratory re- 

 search know well how the discovery of a new fact in science is made 

 at the price of much groping, of misconceptions and of failures, and 

 how these have to be conquered before the truth is learned. Is it 

 reasonable, then, to suppose that it can be otherwise for these great 

 experiments in economic entomology, of which we have just spoken? 

 And if by forced circumstances those who are carrying them on can not 

 be protected by the silence which the learned men of the laboratory 

 enjoy, if the work which they are undertaking is exposed to distortion 

 or exploitation by persons anxious to boast and to give out sensational 

 information . . . these are circumstances which, to our eyes, can only 

 add to their merit and to increase the rights which they have to our 

 esteem. 



If eulogy without reserve should be given to those who have taken 

 part in this great movement in favor of the utilization of beneficial 

 insects, we would have the right, on the other hand, to discuss the 

 too-exclusive and too-optimistic conclusions to which some of the most 

 fervent adherents of the method have been led. 



It is in California above all, and in Australia, as we have said, that 

 the theory has been formulated in the most absolute way. According 

 to the claims of the State Board of Horticulture, of California, no 

 insect is in its original home a pest of sufficient gravity to menace a 

 crop in a serious way, because nature has always placed by its side a 

 parasite capable of holding it in check. Each time that a new enemy 

 reveals itself in a region and begins to undergo exaggerated multi- 



