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NATURE. 



[January 19, 1922 



All this means that we are beginning to realise 

 that insects are our most important rivals in Nature, 

 and that we are beginning to develop our defence. 



While it is true that we are beginning this 

 development, it is equally true that we are only at 

 the start. Looking at it in a broad way, we must 

 go deeply into insect physiology and minute 

 anatomy ; we must study and secure a most perfect 

 knowledge of all of the infinite varieties of in- 

 dividual development from the germ cell to the 

 adult form; we must study all of the aspects of 

 insect behaviour and their responses to all sorts of 

 stimuli — their tropisms of all kinds ; we must study 

 the tremendous complex of natural control, involv- 

 ing as it does a consideration of meteorology, 

 climatology, botany, plant physiology, and all the 

 operations of animal and vegetable parasitism as 

 they affect the Insecta. We must go down to great 

 big fundamentals. 



All this will involve the labours of an army of 

 patient investigators and will occupy very many 

 years — possibly all time to come. But the problem 

 in many of its manifestations is a pressing and 

 immediate one. That is why we are using a chem- 

 ical means of warfare, by spraying our crops with 

 chemical compounds and fumigating our citrus 

 orchards and rhills and warehouses with other 

 chemical compounds, and are developing me- 

 chanical means both for utilising these chem- 

 ical means and for independent action. There 

 is much • room for investigation here. We 

 have only a few simple and effective insect- 

 icides. Among the inorganic compounds we 

 have the arsenates, the lime and sulphur sprays, 

 and recently the fluorides have been coming in. Of 

 the organic substances we use such plant material 

 as the poisons of hellebore and larkspur, pyrethrum 

 and nicotine; and the cyanides and the petroleum 

 emulsions are also very extensively used. No really 

 synthetic organic substances have come into use. 

 Here is a great field for future work. Some of the 

 after happenings of the war have been the use of 

 the army flame-throwers against the swarms of 

 locusts in the South of France, the experimental use 

 against insects of certain of the war gases, and the 

 use of the aeroplane in reconnaissance in the course 

 of the pink bollworm work along the Rio Grande, 

 in the location of beetle-damaged timber in the 

 forests of the North-west, and even in the insect- 

 icidal dusting of dense tree growth in Ohio. The 

 chemists and the entomologists, working co-opera- 

 tivelyi have many valuable discoveries yet to make, 

 and they will surely come. 



All this sort of work goes for immediate relief. 

 Our studies of natural control follow next. It is 

 fortunately true that there are thousands upon thou- 

 sands of species of insects which live at the expense 

 of those that are inimical to man and destroy 

 them in vast numbers ; in fact, as a distinguished 

 physicist, in discussing this topic with me, recently 

 said : "If they would quit fighting among them- 

 selves they would overwhelm the whole vertebrate 



NO. 2725, VOL. 109] 



series." This is, in fact, one of the most important 

 elements in natural control, and is being studied m 

 its many phases by a small but earnest group of 

 workers. 



So far, while we have done some striking things 

 in our efforts at biological control, by importing 

 from one country into another the natural enemies 

 of an injurious species which had itself been acci- 

 dentally introduced, and while we have in some 

 cases secured relief by variations in farm practice 

 or in farm management based upon an intimate 

 knowledge of the biology of certain crop pests, we 

 are only touching the border of the possibilities of 

 natural control. For an understanding of these 

 possibilities we must await the prosecution of long 

 studies. 



Let us summarise. FeAV people realise the critical 

 situation which exists at the present time. Men and 

 nations have always struggled among themselves. 

 War has seemed to be a necessity growing out of 

 the ambition of the human race. It is too much, 

 perhaps, to hope that the lesson w^iich the world 

 learned in the years 1914 to 1918 will be 

 strong enough to prevent the recurrence of inter- 

 national w^ar ; but, at all events, there is a war, not 

 among human beings, but between all humanity and 

 certain forces that are arrayed against it. Man is 

 the dominant type on this terrestrial body ; he has 

 overcome most opposing animate forces ; he has sub- 

 dued or turned to his own use nearly all kinds of 

 living creatures. There still remain, however, the 

 bacteria and protozoa that carry disease and the 

 enormous forces of injurious insects which attack 

 him from every point and constitute to-day 

 his greatest rivals in the control of Nature. They 

 threaten his life daily ; they shorten his food sup- 

 plies, both in his crops while they are growing, and 

 in such supplies after they are harvested and stored, 

 in his meat animals, in his comfort, in his clothing, 

 in his habitations, and in countless other ways. In 

 many ways they are better fitted for existence on 

 this earth than he is. They constitute a much older 

 geological type, and it is a type which had persisted 

 for countless years before he made his appearance, 

 and this persistence has been due to characteristics 

 which he does not possess and cannot acquire — 

 rapidity of multiplication, power of concealment, a 

 defensive armour, and many other factors. With 

 all this in view it wall be necessary for the human 

 species to bring the great group of insects under 

 control, and to do this will demand the services of 

 skilled biologists — thousands of them. We have 

 ignored the insect group to a certain extent on 

 account of the small size of its members, but their 

 small size is one of the great) elements of danger 

 — is one of the great factors of their success in 

 existence and multiplication. 



Let all the departments of biology in our 

 universities and colleges consider this plain state- 

 ment of the situation, and let them begin a con- 

 certed movement to train the men who are needed in 

 this defensive and offensive campaign. 



