6 ANIMAL LIFE AND HUMAN PROGEESS 



earth and the spoils of the chase had at first to be shared with 

 many formidable rivals which have long since disappeared 

 from the scene, but, although the larger competitors have been 

 almost eliminated, mankind has not yet acquired complete 

 mastery of the world's food-suppHes. It is in this field that 

 the activities of the zoologist are perhaps most usefully 

 employed at the present time, when the struggle for food is 

 once more resuming its former intensity. 



I had hoped that it might have been possible to persuade 

 one of our experts in economic zoology to deal with this part 

 of our theme, and it may be regarded as a tribute to its import- 

 ance that the zoologist to whom I applied was already so 

 fully occupied with work of national urgency that it was quite 

 impossible for him to accede to my request. I do not profess 

 to be an economic zoologist myself, but in these abnormal 

 times most of us seem to find ourselves attending to other 

 people's busiaess, and it so happens that, in conjunction with 

 several colleagues at King's College and elsewhere, I have 

 spent much of my time for some months past in the investiga- 

 tion of a problem which may serve to illustrate this part of 

 our subject. 



The problem to which I refer is the protection of our 

 stores of wheat and other cereals from the depredations of 

 destructive insects, and, although as yet only very partially 

 solved, it presents such a variety of interesting and instructive 

 features that it seems worth while to devote a httle time to 

 its consideration this evening. Indeed, it may be taken as 

 a type of one of the largest and most important classes of 

 problems with which the student of applied zoology is con- 

 fronted, and may be used to illustrate not only the nature of 

 the results which he strives to attain but also the methods 

 which he employs. 



The problem is not a new one. In America and in India 

 it has already been attacked with some measure of success, 

 and a fairly extensive literature has grown up around the 

 subject ; but in this country comparatively little has as yet 

 been done, while the matter has lately assumed special im- 

 portance in view of the shortage of our food-supplies and 



