14 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



THE FIRST GENERATION. 



FIRST BROOD OF EGGS. 



Length of incubation. — The eggs of the first brood on an average 

 hatched within 6 or 7 days. Under low temperature the maximum 

 length of time was 10 days. The shortest period of incubation was 

 4 days. (See Table XII.) 



Table XII. — Incubation period of eggs of the first brood laid in rearing cages, Douglas, 



Mich., 1910. 



The so-called "red ring" of the egg appeared from two to three days 

 after egg deposition, and the "black spot" from one to two days pre- 

 vious to hatching. 



The eggs used in these experiments were laid hi cages on pear 

 foliage. Records on the development of the eggs were taken once 

 daily between 9 and 10 o'clock in the morning. 



FIRST BROOD OF LARVAE. 



Time of hatching. — In the field the actual time of hatching and the 

 relative abundance of newly hatched larva? may be fairly well deter- 

 mined from the different data on hand relative to the time of emer- 

 gence of the moths, egg deposition, incubation of eggs, length of 

 feeding of larvae, and the appearance of mature larvae, as shown by the 

 band records. In correlating these facts the time of hatching is estab- 

 lished as given in the diagram of figure 11. 



The earliest eggs were deposited June 17, the maximum oviposition 

 was reached at the close of June, and a few late eggs were laid up to 



