CODLING MOTH IX CENTRAL APPALACHIAN REGION. 



43 



that the codling moth in its development is so responsive to transient 

 weather conditions and other local disturbing factors that the time of 

 appearance of a certain brood in one locality can not be determined 

 with certainty by any mathematical calculation based on the known 

 time of appearance of the same brood in another locality of a known 

 difference in altitude or latitude. It is probable that local differences 

 in humidity, susceptibility to sudden changes in temperature as 

 effected by topography, and, possibly, soil conditions, are more or 

 less direct factors influencing the time of developmental changes in 

 the insect. 



In Table XL the results of these observations are given. In this 

 table use is made of the law laid down some years ago by Dr. A. D. 

 Hopkins that in phenological phenomena a fourth of a degree of lati- 

 tude, or 100 feet in altitude, is equal to one day of time. The table 

 shows that in this particular case the law does not apply. Charlottes- 

 ville, being at the lowest altitude and the most southerly of thestations, 

 is taken as a base and the other points considered in their relation 

 thereto. In considering this table it should be borne in mind that 

 data were collected but twice a week and that the dates given for the 

 first appearance of the insect in its various stages may be from one to 

 three days later than the actual occurrence. Differences in latitude 

 that are equivalent to less than half a day are not considered; those 

 equivalent to more than half a day are counted as full days. 



TABLE XL. Effect of differences in altitude and latitude on the time of appearance of 

 spring-brood and first-brood codling moths and Jlrst-brood larvae. 



