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 eggs. 



Num- 

 ber of 



Date- 



De- 

 posited. 



June 20 

 June 21 



...do 



June 22 



...do 



...do 



June 23 

 June 29 



...do 



June 30 

 July 3 



...do 



...do 



July 4 



...do 



...do 



Hatched. 



June 26 



...do 



June 27 



...do 



June 28 

 June 29 



...do 



July 2 

 July 3 



...do 



July 7 

 July 8 

 July 9 



...do 



Jury 10 

 July 11 



Ineu- 

 bat.ion 

 period. 



Total 

 davs. 



102 



45 



6 



45 



162 



126 



42 



42 



224 



9 



136 



170 



238 



Average incubation period 



Maximum 



Minimum 



Num- 

 ber of 



eggs. 



Parthenogenetic eggs. 



Date- 



De- 

 posited. 



June 20 

 ...do 



June 21 



...do 



...do 



June 22 

 ...do 



June 23 



June 29 



June 30 

 ...do 



July 1 

 ...do.... 

 ...do 



July 2 



Hatched. 



June 25 

 June 27 

 June 26 

 June 27 

 June 28 

 June 27 

 June 28 

 June 29 

 July 2 

 July 3 

 July 4 



...do 



July 5 

 July 6 



...do 



Incu- 

 bation 

 period. 



Total 

 days. 



145 

 7 



265 

 12 

 21 

 30 

 84 

 24 

 21 



192 



20 



27 



12 



5 



4 



Average incubation period . 



Maximum 



Minimum 



4.3 



7 

 3 



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

 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 larvae were reared, 6 of them pupating. Table X 

 a summary of the Length of larval life of all larva; reared. 



