432 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 31 



Ever since man began supplying himself with food by tilling the 

 soil, he has, no doubt, had to fight six-legged enemies of his crops. 

 And when our agrarian ancestors made more or less intelligent ob- 

 servations on them, they probably perceived also, though more rarely, 

 that certain kinds make their living by preying upon, or by eating, 

 the bodies of their own relatives. And as observations in the field 

 of natural history became more purj)oseful and systematic, the idea 

 of pitting the latter against the former, the benefactor against the 

 foe, probably grew, in a few minds, to a conviction and a personal 

 experiment, and eventually to practice. Doctor Howard (1)^ tells 

 us that the " gardeners and florists in England for very many years 

 have recognized the value of the ladybirds and have transferred them 

 from one plat to another." But a similar use of parasites is not 

 likely to have been made at that time on account of their small size, 

 and chiefly because of the general lack of knowledge even regarding 

 the nature of their habits. It is not too much to say that no one 

 knew that such a phenomenon as parasitism existed until certain 

 naturalists (1, pp. 16-17) discovered it in the seventeenth century. 

 Aldrovandi, in 1602, is supposed (1, p. 16) to have been the "first 

 to observe the exit of the larvae of Apanfeles glonieratus L.", a com- 

 mon small wasplike parasite of the imported cabbage worm. But it 

 was probably not until more than a half century later that Vallisnieri 

 (1661-1730) discovered (1, p. 17) " the existence of true, parasitic 

 insects " and the real nature of insect parasitism. " Reaumur (1683- 

 1757) and DeGeer (1720-1778) each studied the life histories of liv- 

 ing insects with great care and, among them, worked out the biology 

 of a number of parasites." Ratzeburg observed the bionomics of 

 Hymenoptera parasitic on forest insects, but did not believe that 

 their efficiency could be increased by man. 



Hence, although several biologists had become familiar vrith the 

 fact of parasitism, and apparently considered that man might utilize 

 it in control, the artificial manipulation of parasites was not defi- 

 nitely suggested until after the middle of the nineteenth century. 

 Earlier hints at the feasibility of biological factors for pest control 

 applied to predacious forms, chiefly the lady beetles and ground 

 beetles, whose manner of checking their prey b}^ direct feeding was 

 more easily comprehended generally. Hence, the movement for the 

 use of parasitic insects in what we now call biological control has 

 been begun and carried forward in the past nine decades, and the 

 outstanding ingenious accomplishments of an extensive and practical 

 nature are the work of the past 40 j^ears. and fall mainly within the 

 lifetime of that chief enthusiast for, and sponsor of, the utilization 



* Numbers refer to list of literature cited at the end of this article. 



