47 



effective temperature is shown by a dotted line, man}' interesting facts 

 in regard to the temperature can be observed. It must be noted, 

 however, that the number of larva? caught on any given da}^ is influ- 

 enced by the temperature of the preceding da}^, as most of the larvas 

 enter the bands at night, some time before midnight, and that they 

 are usually killed and counted some time the following morning, 

 while the obserA'ations upon the temperature were taken at 6 a. m. 



Fig. 6. — Weekly summary of Mr. Gibson's band record. 



and 6 p. m. The great rise which occurred on June S-i was prol)abl3^ 

 due in a great measure to the fact that the bands were placed upon 

 the trees on the 21st. The fall in the number of larvje on Jiuie '24:, 

 the rise on J una 27, the fall on June 30, the rise on July 1 and 2, and 

 the fall on Jul}' 4 can be partially accounted for b}^ the corresponding 

 rise and fall of the temperature. From about July 5 to August 4 the 



Fig. 7.— Band record made by William A. George, Caldwell, Idaho, In 1901. 



temperature was high, but there was no corresponding rise m the 

 number of larva?, as there were no larva? ready to enter the bands, the 

 majority of the insects being in the moth, egg, and younger larval 

 stages. This interval of few larvae marks the time between the 

 maxima of the generations entering the bands. In the second maxi- 

 mum it can be noted that the rise and fall of the number of larvie is 



