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. 
Date of— Date of— 
No. Days of No. Days of 
of obser- incuba- || of obser- incuba- 
vation. | Deposi- | Hatch- tion. vation. | Deposi- | Hatch- tion. 
tion. ing. tion. ing. 
oes June 23 | June 29 6 | 9 
Ps eis se June 24 |...do..... 5 8 
Seeks June 25} July 1 6 | 7 
ANE ys tans dotzeae Julyr2 fe 8 
Lease June 26 |..-do-.... 6 | 7 
Grease. doze--- July 3 @| 6 
ener June 27 | July 4 of 7 
eae Goeeee | aulyoe) 8 6 
OR eee June 28 | July 6 8 | 5 
OD eee June 29 | July 7 8 | 6 
Tee Ce soce|| wulky fe 9 5 
1 eae dow...) July 19 10 6 
Bee ei ere June 30] July 8 8 6 
Ae Bd ie July 1] July 9 8 7 
1S eee eee dOkeu July 10 9 8 
iGo ae Pe dost ase July il 10 7 
N/aSaaoe July tac dOsenee 9 8 
UeMosese PeedOEseee July 12 10 7 
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. 
TasLe XIII.—Jncubation period of first-brood eggs. Summary of Table X IT. 
Days of 
Observations. incuba- 
tion. 
DA VOTE Es n= cteveis) Yisystampetovarte 7.33 
Wie patron bangles ep te Ae sea 10 
Minimum 5559s Sees 5 
