80 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES 



THE FIRST GENERATION. 



FIRST-BROOD EGGS. 



Incubation period. — In the preceding pages the time and extent of 

 egg deposition have been considered as habits of the moths. In view 

 of the abundance of eggs laid on the apples in the cages, it was not pos- 

 sible to count the eggs and determine the incubation period for individ- 

 ual eggs. But, as shown in Table XII, records were taken at the time 

 of hatching of the first and the last eggs of each group of apples con- 

 taining eggs of a given age, which merely shows in a general way the 

 extent of the variability during the incubation. 



Table XII. — First-brood eggs. Incubation period of eggs laid in rearing cages. 



No. 



of obser- 

 vation. 



Date of— 



Days of 

 incuba- 

 tion. 



No. 



of obser- 

 vation. 



Date of— 



Days of 

 incuba- 

 tion. 



Deposi- 

 tion. 



Hatch- 

 ing. 



Deposi- 

 tion. 



Hatch- 

 ing. 



1 



2 



3 



4 



5 



6 



June 23 

 June 24 

 June 25 



...do 



June 26 



...do 



June 29 



...do 



July 1 

 July 2 



...do 



July 3 

 July 4 

 July 5 

 July 6 

 July 7 

 July 8 

 July 9 

 July 8 

 July 9 

 July 10 

 July 11 



...do 



July 12 



6 

 5 

 6 

 7 

 6 

 7 

 7 

 8 

 8 

 8 

 9 



10 

 8 

 8 

 9 



10 

 9 



10 



19 



20 



21 



22 



23 



24 



25 



26 



27 



28 



July 3 

 Julv 4 

 July 5 



...do 



July 6 

 July 8 



...do 



July 9 

 July 10 



...do 



July 12 



...do 



...do 



July 13 



...do 



July 14 

 July 15 



...do 



...do 



July 16 



...do 



July 17 

 July 18 

 July 19 

 July 21 



...do 



July 22 



...do 



9 



8 

 7 

 8 

 7 

 6 



6 

 5 



6 

 5 



6 



' 6 



7 



8 



7 

 8 



7 



7 



8 



June 27 

 ...do.... 



9 



10 



11 



June 28 

 June 29 

 ...do.... 



29 



30 



July 11 

 ...do 



12 



...do.... 



13 



14 



15 



June 30 

 July 1 

 ...do 



31 



32 



July 12 

 ...do 



33 



34 



35 



36 



July 13 

 July 14 



...do 



July 15 



16 



17 



18 



...do 



July 2 

 ...do 







The difference of one to two days in the time of hatching indicates 

 an existing difference in the embryological development originating 

 previous to the time of oviposition. Similar observations were made 

 in 1909 by the writer with eggs of the grape root- worm which had all 

 been laid by a single female at the same time. On hatching, these 

 eggs showed a variation of 2 days in the time of incubation. Table 

 XII, representing a summary of observations of the previous table, 

 shows an average of 7.33 days for the entire egg period, with a maxi- 

 mum of 10 days and a minimum of 5 days. 



Table XIII. — Incubation period of first-brood eggs. Summary of Table XII. 



Observations. 



Days of 

 incuba- 

 tion. 





7.33 

 10 

 5 









