12 



The time elapsing between the emergence of the moth and the depo- 

 sition of eggs in the cages has A'aried between 1 and 9 days, with an 

 average of 6.7 days. 



The number of eggs laid in confinement has varied between 2 and 

 50, and nearly every one has hatched except where males were not 

 confined with the female. Of 65 eggs inclosed in paper sacks upon 

 the trees only 2 failed to hatch. Nearly all the eggs seem to be fertile 

 at Fort Collins, but at the same time there are many more eggshells 

 to be found upon the apples than worm holes in them, which would 

 indicate a large mortality among the small worms. In our counts we 

 have found nearh' 90 i3er cent of these eggs upon the free surface of 

 the apples and the remainder ui^on the leaves. 



CHANGES IN THE EGG DURING INCUBATION. 



When the egg is first laid it is of a pearly white color. Later 

 there apiDears upon it a faint red ring, marking the position of the 

 forming embryo. A day later this ring becomes more distinct and 

 later disappears, and in its stead there is a dark central spot, produced 

 by the black head and cervical shield of the embryo. When the larva 

 leaves the egg the remaining shell appears like a fresh egg, except 

 that it is very flat and along one side the slit from which the larva 

 made its exit can usually be seen. Notes bj^ an assistant, Mr. E. P. 

 Taylor, upon 57 freshly laid eggs show that the red ring appears upon 

 the second or third day after the egg is laid, the disappearance of the 

 ring and the apj)earance of the dark spot 2 to 3 days later, and the 

 hatching of the egg on the first or second da}^ after the appearance of 

 the dark spot. These eggs were deposited in the breeding cages. 

 Eggs observed in the orchard required about 1 da}^ more to hatch, 

 probabl}^ on account of the lower temperature during night, making 

 the average incubation period 7 and a fraction daj^s. Rilej^ gave this 

 period as from 4 to 10 daj^s, Washburn as 5 to 10 da3^s, and Slinger- 

 land as about a week. We have found the time to vary between 6 

 and 8 days in the laboratory where the temperature ranged between 

 68° during the night and 75° during the middle of the day. For eggs 

 kept in a greenhouse where the temi3erature ran to 110° during the 

 middle of the day, the hatching period was 6 days. The records of 

 the hatching of eggs in these two rooms is as follows: 



Table III. — Coinparison of egg-hatching records i)i a cool and a hot room. 





Cool room: temper- 

 ature, between (J8° 

 and 75° F. 



Hot room in green- 

 house: tempera- 

 ture. 110° at midday. 



Niimbei' of eggs 



15 



Aug. 11 (night) 



Aug. li 



Aug.lT 



Aug. 18 (morning) . . 



15. 



Eggs laid 



Distinct red ring 



Dark center 



Hatched 



Aug. 11 (night). 



Aug. U. 



Aug. It). 



Aug. 17 (evening). 



1 



Eleven eggs hatched in each of the above lots, the difference in 

 time being from evening one day to morning of the next. The time 



