CODLIXCt moth in CENTKAL APPALACHIAN EEGION. 



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, susceptibOity to sudden changes in temperature as 

 effected by topogi'aphy, 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 the stations, 

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

 thereto. In considering tliis 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 haK a day are counted as full days. 



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

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



Locality. 



Charlottesville, Va... 



Orcenwood, Va 



Ilagcretown, M d 



W inchcster, Va 



Ffahersvllle, Va 



French Creek, W. Va 

 I'lckena, W. Va 



Year. 



1912 

 1913 

 1!)I2 



v.n:i 



1912 

 191:5 

 1912 

 19)3 

 1912 

 19i;{ 

 1912 

 191.', 

 1912 

 1913 



Date of 

 emer- 

 gence of 



first 

 spring- 

 brood 

 mollis. 



May 7 

 Apr. 18 

 May 8 



May 30 

 .May 1,5 

 May 22 

 May r, 

 May 18 

 May 3 

 May 13 

 May 

 Juno 13 

 June 21 



Date of 

 first 

 larva3 



collected 

 under 

 bands. 



Juno 

 Juno 5 

 June 6 



Juno 29 

 June 27 

 June 19 

 Juno 17 

 Juno 11 

 Juno 14 

 Juno 24 

 July r, 

 July 31 



Date of 

 emer- 

 gence of 

 first- 

 brood 

 moths. 



Juno 20 

 June 14 

 June 23 



July 13 



July H 



July 9 



Juno 30 



July 2 



July 20 

 July 23 

 Auk. 20 



Elevation 



above sea 



level. 



Feet. 



400 

 400 

 900 



500 



750 

 7.'-)0 



i,r,m 

 i,rm) 



1,(100 

 1,(100 

 3, .'■.(K) 



Elevation 

 above 



Charlottes- 

 ville. 



Feet. 



500 



100 



1.50 



3,50 



3,50 



1,100 



1, 100 



1,200 



1,200 



3, 100 



