WALNUT APHIDES IN CALIFORNIA. 



29 



Table IX. — Life-cycle record of the progeny of four viviparous females of Monellia 

 caryella, Walnut Creek, Cal., 1912 — Continued. 



FEMALE NO. 3; DEPOSITED 16 YOUNG. 





Date of — 



Form of individual. 





No. of larva. 



Hatch- 

 ing. 



Molt 1. 



Molt 2. 



Molt 3. 



Molt 4 

 (becom- 

 ing 

 adult). 



Life 

 cycle. 



1 



Oct. 16 

 16 

 16 

 17 

 17 

 17 

 17 

 18 

 18 



Oct. 21 

 21 

 21 



(?) 

 (?) 

 (?) 

 (?) 

 (?) 

 (?) 



Oct. 27 

 27 

 27 



(?) 



(?) 



(?) 



(?) 



(?) 



(?) 



Nov. 3 

 3 

 3 



(?) 



(?) 



(?) 



(?) 



(?) 



(?) 



Nov. 7 

 7 

 7 

 8 

 8 

 8 

 8 

 8 

 9 



Oviparous female 



do 



Days. 

 22 



2 



22 



3 



do 



22 



4 



do 



22 



5. . 



do 



22 



6 



do 



22 



7... 



do 



22 



8 



do 



21 



9 



do 



22 



10i 



do 





Hi 













do 





121 













do '.. . 





13i 













do 





141 













do 





151.. 













do 





161 













do 





















FEMALE NO. 4; DEPOSITED 8 YOUNG. 



1 



Oct. 18 

 18 

 18 

 18 



Oct. 22 

 22 

 22 

 22 



Oct. 27 

 27 



27 

 27 



Nov. 2 

 3 

 4 

 4 



Nov. 



7 

 9 

 9 

 9 



Oviparous female 



do 



do 



20 



2 



22 



3 



22 



4 



do 



22 



51 



do 





6' 













do. . 





71 













do 





8i 













do 





















Died prematurely. 

 SUMMARY. 



Life cycle (20 oviparous females). 



Maximumt 



Minimum 



Average 



First instar (13 individuals), average. . 

 Second instar (13 individuals), average. 

 Third instar (11 individuals), average.. 

 Fourth instar (11 individuals), average 



Days. 



22 



14 



18.92 

 3.7 

 4.5 

 5.7 

 5.6 



The viviparous forms, so far as the author has observed, all 

 develop wings. 



The eggs of this aphis are larger than those of the American walnut 

 aphis and measure on the average 0.536 mm. in length and 0.222 mm. 

 in maximum width. They are elongate-oval in shape, rather feebly 

 shining, and have a softer shell than is found in the eggs of the 

 majority of plant-lice, but one not so soft as is that of CJiromapMs 

 juglandicola. They are placed either singly or in groups of two or 

 three around the axils of the buds or in crevices in the bark and in 

 scars caused by fallen leaves on the smaller limbs and twigs. Ovipo- 

 sition is in. progress during the months of October and November, each 

 oviparous female laying on the average about 12 eggs. Owing to the 



