64 



BULLETIN 1235, U. S. DEPARTMENT OF AGRICULTURE. 



the spring brood of moths, in order to time properly the first cover 

 application of spray. These points were made the subjects of 

 experiments in 1919 and 1920, both on moths of the spring brood 

 and on those of the first brood, and in 1921 on moths of the first 

 brood. 



Moths of the spring brood. — In 1919, seven cages of moths, each 

 containing approximately 25 individuals, were observed daily, begin- 

 ning at 6 a. m., and observations were made every three hours, 

 except at 3 a. m., during the period from June 3 to June 8, inclusive. 

 The temperature at the time of making each observation was also 

 noted. The results of these observations are given in Table 52, 

 the number of eggs deposited in all the jars for any given period 

 being added together. No eggs were deposited between midnight 

 and 6 a. m., and thereafter the number increased for each period, 

 reaching a maximum of 57.30 per cent of the total during the 3-hour 

 period ending at 6 p. m. Between 3 p. m. and 9. p. m., 80.67 per 

 cent of the total eggs were deposited. 



Table 52. — Time of oviposition by codling moths of the spring brood, in 3-hour 

 periods, Yakima, Wash., 1919. 



Hour of 

 observation. 



Date of oviposition. 



June 3 



June 4 



June 5 



June 6 



June 7 



June 8 



6 a. m 



9 a. m 



12 noon 



3 p. m 



6 p. m 



9 p. m 



12 midnight . . . 



Total.... 



55 







3 



9 



70 



255 



104 



4 



53.83 

 63.83 

 72.17 

 75.00 

 70.17 

 57. 83 

 52.00 



160 



67 



0.00 

 0.67 

 2.02 

 15.73 

 57.30 

 23.37 

 0.90 



Total number of eggs on foliage 394 



Total number of eggs on cages .51 



Per cent of eggs on foliage SS. 54 



In 1920, five cages of moths were used for observations on the 

 time of oviposition, the results of these observations being pre- 

 sented in Table 53. During the time these moths were under special 

 observation they deposited no eggs between midnight and 9 a. m. 

 Thereafter, the number increased for each succeeding 3-hour period 

 until the period ending 6 p. m., during which 40.92 per cent of the 

 total were deposited. Between 3 p. m. and 9 p. m., 68.97 per cent of 

 all eggs were deposited. 



