366 ANNUAL KEPORT SMITHSONIAN INSTITUTION, 1925 



the inuividiKil species, and has been able to draw from all this the 

 following conclusion : 



The insect fauna of a given region is not a single stable unit, varying only in 

 abundance from year to year, but is a composite of smaller groups, each of 

 which has more or less definite optimum. The composition of the fauna in a 

 given season is very definitely related to the climatic conditions prevailing at 

 the time of growth. Three dry years culminating in 1919 enormously in- 

 creased the proportion of prairie elements in the Bozeman fauna, while reduc- 

 ing the eastern and mountain forms. The trend of the climate toward normal 

 has resulted by 1923 in a great reduction in these prairie intruders, and the 

 reestablishment of the eastern and mountain forms. How much farther thi.s 

 movement will go can not be predicted, but it is certain that a return of dry 

 weather will reverse the direction of the trend. 



I select this instance because it concerns a paper that was published 

 only the other day, but recent entomological and ecological journals 

 contain numbers of articles of equal or greater significance. Wliat 

 an advance ! In the general warfare again.st insects tho.se conclu- 

 sions will seem to have no immediate bearing upon any problem, 

 but they are valuable and very suggestive and indicate great prog- 

 ress in entomological thought and methods. 



I find a confident prophecy as to the effect of work of this character 

 in a paper by C. H. T. Townsend in the journal Ecology for January, 

 1924. He says in closing: 



Environment work will l)e the first and last steps in the insect control of the 

 future. The normal favorable environment must be changed to an unfavorable 

 one. Given the factor values in the environment classes to which the insects' 

 phases are subjected, with the insects' responses to the same, we are in the 

 most advantageous position for deciding which phase to attack and which en- 

 vironment class to manipulate in order to gain control. 



Here the factor values include heat, sunlight, rainfall, atmospheric 

 humidity, atmospheric pressure, wind, soil texture, soil moisture, 

 vegetation, food supply, predators, parasites, and disease. 



I remind you of this prophecy without absolutely complete indorse- 

 ment, but as an especially notable paragraph. 



We must not leave this subject of ecology without mention of Hop- 

 kins' promising work on bioclimatic laws. It is a subject to which 

 this able thinker is now fortunately able to devote his principal at- 

 tention. He has already arrived at conclusions of far-reaching 

 value — far beyond the confines of economic entomology — and it is 

 hoped that this great work will receive the appreciation it deserves. 



To be able to know precisely and definitely what creature is before 

 one — to be able to write about it in such a way that all other Avorkers 

 will understand — necessitates a system of classification and the nam- 

 ing and technical description of a host of forms. The comparative 

 stuSy of morphological characters, of course, indicates relationships. 



