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. 









Date of— 





Duration of— 



Xo of 



Date of 















obser- 

 vation. 



egg depo- 

 sition. 



Appear- 

 ance of red 

 ring. 



Appear- 

 ance of 

 black spot. 



Hatching. 



Red 

 ring. 



Black 

 spot. 



Incu- 

 bation. 













Days. 



Days. 



Days. 



1 

 2 

 3 



June 20 

 .do 







June 29 

 June 30 

 June 29 







9 

 10 













June 22 





June 28 





6 



4 



...do 





...do 



June 30 





6 



8 



5 

 6 



June 24 







July 1 



July 2 



. . . do 







7 











7 

 8 



June 26 











6 







July 3 

 July 4 

 July 5 

 July 4 

 July 5 

 July 6 







9 



June 28 











G 



10 



...do 













11 



June 29 





July 3 

 ...do 





4 



5 



12 

 13 



...do 





----- 



4 

 5 



6 

 6 



June 30 



July 3 



July 5 



14 



...do 



...do 



...do 



July 7 



3 



5 



/ 



15 



July 1 



...do 



July 6 



..do 



2 



5 



6 



16 



...do 



...do 



...do 



July 8 



2 



5 



7 



17 



July 2 



July 5 



July 7 



..do 



3 



5 



6 



18 



July 3 



July 6 



July 8 



July 9 



3 



5 



6 



19 



...do 



...do 



...do 



July 10 



3 



5 



i 



20 



July 4 



...do 



July 9 



...do 



2 



5 



6 



21 



...do 



...do 



July 10 



July 12 



2 



6 



8 



22 



July 6 



July 9 



July 11 



July 13 



3 



5 



7 



23 



...do 



...do 



...do 



July 14 



3 



5 



8 



24 



July 7 



...do 



...do 



July 13 



2 



4 



6 



25 



July 8 



July 10 



July 12 



July 14 



2 



4 



6 



26 



July 9 



July 12 



July 14 



July 15 



3 







6 



27 



...do 



July 13 



...do 



July 16 



4 







7 



28 



July 12 



July 14 



July 15 



...do...... 



2 



3 



4 



29 



...do 



...do 



...do 



July 17 



2 



3 







30 



...do 



...do 



July 16 



July 18 



2 



4 



6 





2.5 



4.7 



6.6 





lum 









4 

 2 



6 



3 



10 



4 



Minim 



urn 



















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 in 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 larvae 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 



