4S THE EEPORT OF THE No. 36 



It seems to me tliat Dr. Hopkins' Bit climatic Law is an important contri- 

 bution to service inasmuch as it is based on j)hen(jb)gical phencimcna which are 

 the best means of determining the intluence of all the complex factors that play 

 upon plant and animal life. 



I have already referred to the use of the Law in the control of the Hessian Fly. 

 Dr. Hopkins has used it in connection with certain forest insects, viz., the Southern 

 Pine Beetle (Dendroctonus frontalis), the Western Pine Beetle (D. hrevicomis), 

 the Mountain Pine Beetle {D. niontkohie), and the Pine Bark Louse or Spruce 

 Gall Louse (Pineus strohi). 



By means of a map-calendar the dates for the .beginning and ending of control 

 measures between the autumn and spring flights can be recommended, in the ease 

 of the Pine Beetles, and in the case of the Pine Bark Louse the date of hatching 

 and time of moving about. 



Dr. Hopkins believes that the Law can be apjdied with great advantage in 

 farm practice as a means of determining the dates of best seeding and harvesting 

 for the production of maximum crops. While he has shown the application of 

 the Law to winter and spring wheat he is of the o])inion that it can be applied 

 equally Avell to all kinds of crops. 



Moreover, it can be used for the making of reliable spray calendars in orchard 

 practice for the control of insect and fungus diseases. 



This Law, moreover, is of value in determining the northern limit in the 

 geographical distribution of species of plants and animals. It is, therefore, a 

 valuable supplement to Merriam's Avork on Life Zone§. 



Regarding the value of phenology Dr. Hopkins says : '' Properly recorded and 

 correctly -interpreted there is nothing perhaps to equal the records of the dates 

 of periodical events in plants and animals as indices to the bioclimatic character 

 of a place or local area, because such events are in direct response, not to one or 

 a few, but to all the complex elements and factors of the environment which no 

 artificial instrument or set of instruments yet available will record. In other 

 words, while species and varieties and even individuals of the same species and 

 variety respond in a more or less different degree to the same complex influences, 

 there are certain constant elements in the response of individuals and groups of 

 varieties and species which, if properly interpreted, will sepve as a key to the 

 bioclimatic character and conditions which distinguish a particular region, locality, 

 or place from that of other nearby or distant ones. 



The Bioclimatic Law in Canada. 



Most of the data from which Dr. Hopkins prepared liis maps were obtained 

 from the United States, and it will be observed that the dej^nrtures from the Law 

 constants are practically absent from the Canadian section of his maps. Xo doubt 

 the reason for this absence was the lack of sufficient data from Canada. 



The writer believes, however, that Canada has the data if they can only be 

 compiled. This country has not only a large numlier of experiment stations 

 scattered from the Atlantic to the Pacific, but also a large inimber of reports 

 prepared by Federal and Provincial agencies, that could supply the necessary data 

 relating to phenological phenomena. A compilation of such data would be most 

 valuable in extending the practical application of the Bioclimatic Law to the 

 different sections of Canada. The writer expresses the hope that some competent 



