THE DOCK FALSE-WORM. 



23 



SECOND GENERATION. 



Incubation period of second-brood eggs. — The length of the second- 

 brood egg stage is shorter than that of the first, owing to the warmer 

 weather at this time, the fertile eggs having an average incubation 

 period of 4.8 days, and the parthenogenetic eggs an average period 

 of 4.3 days. The records for 238 fertile eggs and 202 parthenogenetic 

 eggs are given in Table IX. 



Table IX. — Length of the incubation period of second-brood eggs of the dock false-worm, 



Wenatchee, Wash., 1915. 



Fertile < 



Num- 

 ber of 



238 



Date- 



De- 

 posited. 



June 

 June 



...do. 

 June 



...do. 



...do. 

 June 

 June 



...do. 

 June 

 July 



...do. 



...do. 

 July 



...do. 



...do. 



2_» 



Hatched. 



June 26 

 ...do 



June 27 



...do 



June 28 

 June 29 



...do 



July 2 

 July 3 



...do 



July 7 

 July 8 

 July 9 



...do 



July 10 

 July 11 



Incu- 

 bation 

 period. 



Average incubation period. 



Maximum 



Minimum 



Total 

 days. 



102 



45 



6 



45 



162 



126 



42 



42 



224 



9 



136 



170 



6 



25 



6 



14 



1,160 





Parthenogenetic eggs. 







Date- 







Num- 

 ber of 





Incu- 

 bation 



Total 

 days. 







eggs. 



De- 

 posited. 



Hatched. 



period. 



29 



June 20 



June 25 



5 



145 



1 



...do 



June 27 



7 



7 



53 



June 21 



June 26 



5 



265 



2 



...do 



June 27 



6 



12 



3 



...do 



June 28 



7 



21 



6 



June 22 



June 27 



5 



30 



14 



...do 



June 28 



6 



84 



4 



June 23 



June 29 



6 



24 



7 



June 29 



July 2 



3 



21 



64 



June 30 



July 3 



3 



192 ' 



5 



...do 



July 4 



4 



20 



9 



July 1 



...do 



3 



27 



3 



...do 



July 5 



4 



12 



1 



...do. ... 



July 6 



5 



5 



1 



July 2 



...do 



4 



4 



202 





869 



Average incubation period 



..4.3 



Maxim 





.. 7 



Minimi 



lm 



.. 3 













Length of life of second-brood larvse by instars. — Of 43 larvse 

 which were reared from fertile eggs only 17 reached the pupal 

 stage. The greatest mortality, due to lack of moisture, occurred 

 after the mature larvse had formed their pupal cells. Forty-seven 

 parthenogenetic larvse were reared, 6 of them pupating. Table X 

 gives a summary of the length of larval life of all larvse reared. 



