December, '14] PARKS: TEMPERATURE AND OVIPOSITION OF PHYTONOMUS 419 



chart. The highest record for egg deposition was reached May 18, 

 when an average of twenty-six eggs per female were deposited. This 

 day also had the highest mean temperature of any day previous to 

 June 6. The most of the eggs were deposited during May, and the 

 rate of oviposition rapidly declined after the first of June, but was still 

 influenced by changes in temperature, as shown by the record of 

 June 24. 



The temperature records were secured from the office of the United 

 States Weather Bureau at Salt Lake City. The relation between the 

 curves representing temperature variation and oviposition record is 

 very noticeable, and the mean daily temperature seemingly affects 

 the progress of oviposition until well into the. summer. 



The accompanying table shows the number of eggs deposited by 

 each female first used in the oviposition experiments, or until she died 

 and was replaced by another. The largest number of eggs deposited 

 by any of these was 1,184, and the average for the series was 726 eggs 

 per female. This is a fair estimate of the average number of eggs 

 deposited by each female beetle in the fields during the season: 



Oviposition Record of Sixteen Beetles in 1912 (Phytonomus posticus Gyll) 



Average 



In a series of experiments with eleven females collected from hiber- 

 nation December 20, 1911, and allowed to deposit eggs in the warm 

 laboratory room during the winter and spring, the average number of 

 eggs deposited was 913. One beetle deposited 1,918 eggs. 



