56 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 1 



THE RELATION OF TEMPERATURE TO THE HIBER- 

 NATION OF INSECTS 



By E. D. Sanderson, Durham, N. H. 



Three years ago at the Philadelphia meeting of this association the 

 writer advanced a hypothesis for determining the time of maximum 

 emergence of the Mexican cotton boll weevil. Subsequent observa- 

 tions by others have tended to discredit the correctness of the method 

 then advanced, but it served to call attention to the fact that "the 

 time of emergence of insects from hibernation and the date upon 

 which they begin oviposition or normal activity is dependent upon 

 well-defined physical laws" which should be determined, and the 

 writer is of the opinion that careful study of the large amount of 

 data now accumulating concerning the time of emergence of the boll 

 weevil will reveal the laws governing the time of its appearance. 



Since then, with the aid of assistants and students, I have made a 

 number of experiments principally with the tent caterpillar {Malaco- 

 soma americana) , the brown-tail moth {Euproctis chrysorrhoea) , and 

 the codling moth (Carpocapsa pomonella) , in an endeavor to deter- 

 mine the relation of temperature to the hibernation of insects. Only 

 a beginning has been made and as we get deeper into the subject we 

 find that it is an exceedingly complex one and is closely bound up 

 with fundamental problems of physiology and heredity. There are 

 a few points, however, which may well be brought to your attention 

 at this time. 



It has been customary in the study of meteorological and biological 

 data concerning temperature to use the mean daily temperature in 

 accumulating the amount of temperature involved in any phenomena. 

 But it is evident that if the day be cloudy and the sun shine for a 

 short time at noon that the mean for that day will be much higher 

 than the actual mean temperature which occurred during that day. 

 We have therefore resorted to the use of recording thermographs of 

 the Reichard or Short and Mason type, such as are in use by the U. S. 

 Weather Bureau, which, with frequent standardization, show the 

 actual temperature for the whole day. The polygon covering the 

 temperature for the day is then measured with a polar planimeter 

 and the actual mean temperature for the day is thus secured. It is 

 found that frequently a difference of ten degrees occurs in greenhouses 

 between the mean secured from the maximum and minimum and the 

 true mean thus secured with a thermograph. Such records are espe- 

 cially important where a glass house is being used for experiments, 

 and it would seem that this is the only accurate method of recording 

 temperature where an exact study of temperature is desired for bio- 



