14 BULLETIlSr 438, U. S. DEPAETMEXT OF AGRICULTURE. 



Table YIl.— Larval life history of the pear leaf-worm at Wenatchee, Wash., 1915. 



No. 



Date of— 



Length in days. 



Hatch- 

 ing. 



1st molt. 



2d molt. 



3d molt. 



Cocoon. 



1 



2 



3 



4 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



15 



16 



17 



18 



19 



20 



21 



22 



23 



24 



25 



26 



27 



28 



29 



30 



31 



32 



33 



34 



35 



36 



37 



Apr. 16 

 Apr. 18 



...do 



Apr. 19 



...do 



...do 



Apr. 23 

 Apr. 25 



...do.... 



...do.... 

 Apr. 26 



...do 









7 

 7 

 7 

 6 

 7 

 7 

 7 

 7 

 7 

 7 

 7 

 5 

 5 

 5 

 6 

 6 

 6 

 5 

 5 

 5 

 6 

 6 

 7 

 5 

 5 









May 2 

 Apr. 29 

 Apr. 28 

 Apr. 30 

 May 1 

 ...do 







7 

 4 

 3 

 4 

 5 

 5 

 8 







May 7 

 May 6 



May 14 



8 

 8 



7 













...do 



...do 









...do 



...do 



May 4 









...do 



...do 













...do 



...do 



j 









...do 



...do 



i 











Apr. 21 

 ...do 



...do.... 

 ...do 



May 2 

 May 3 







6 



7 















...do. ... 



...do 











...do.... 

 .do 



Apr. 27 



Mav 5 





8 







. .do 









Apr. 22 



Apr. 23 



.do .... 



Apr. 28 Mav 5 





7 

 7 

 7 







...do 



...do 



...do 









__.rlo . i_ . _ 







...do 



...do...-. 







...do.... 

 ...do 



Apr. 29 

 .. .do. . .. 









( 







...do.... 

 Apr. 24 

 ...do 



Apr. 30 









Apr. 29 

 ...do 



1 







i i 











Apr. 29 j May 7 

 May 8 May 17 

 May 9 May 15 







8 

 9 

 6 

 6 



8 

 8 

 8 

 7 



■■"e" 



10 

 9 

 10 





































May 15 May 23 

 -do. . i -do. . 













I 



















May 17 



May 24 

 Apr. 23 

 May 8 

 May 12 

 do 











Apr. 29 

 May 18 

 May 21 



May 22 

























































Table Mill .—Summary of Table VII. 



Instar. 



Maximum. 



Minimum. 



Average. 



1. 

 2. 

 3. 



4. 





Days. 



7 



8 



9 



10 



Days. 

 5 

 3 

 6 

 6 



Days. 

 6.1 

 6.0 

 7.6 



8.4 









Total ;. 





28.1 





1 



In ascertaining the larval life history at Wenatchee, it was neces- 

 sary, owing to the distance of the infested orchard, to rear the larvse 

 on leaves kept in water in the outdoor rearmg shelter. These had 

 to be renewed every 4 or 5 days, and the larvse transferred to the 

 fresh leaves. It will be noted that there was a high mortahty among 

 the larvse, and this may be attributed to the fact that the larvae had 

 to be handled more or less, and that they did not always have per- 

 fectly fresh food upon which to feed. It is probable, also, that the 

 periods between molts were lengthened by this abnormal method of 

 rearing, although observations in the field indicate that the figures 

 for the total larval life are approximately correct. In 1915 most of 



