30 



BULLETIN 265, U, S. DEPARTMENT OF AGRICULTURE. 



Table XX. — Length of partial life cycle of the fourth generation of the dock false-worm, 

 Wenatchee, Wash., 1915 — Continued. 



Normal individuals. 



Indi- 

 vidual 

 No. 



Date of — 



Egg dep- 

 osition. 



Aug. 19 

 Aug. 20 

 ..do.... 

 ..do.... 

 Aug. 21 

 ...do.... 

 ..do.... 



Hatching. 



Aug. 23 

 Aug. 24' 

 ...do.... 

 Aug. 26 

 ...do.... 



...do 



Aug. 27 



Forming 

 pupal 

 cell. 



Sept. 18 

 ...do.... 

 Sept. 19 

 ...do... 

 Sept. 22 

 Oct. 4 

 Sept. 24 



Total 



Average number of days . 



Days in — 



Egg 

 stage. 



34 



Larval 



195 



27.8 



Aver 

 agepar- 

 tial life 

 cvcle in 



229 

 32.7 



Maximum life cycle, 44 days; minimum, 29 days. 



SUMMARY OF LIFE-HISTORY STUDIES. 



Table XXI gives a summary of the length of each stage of each 

 generation of the dock false-worm, as worked out at Wenatchee, 

 Wash., in 1915. The column marked "Total life cycle in days" 

 gives the time elapsing between egg deposition and emergence of 

 adult, and the last column gives the time elapsing between the egg 

 deposition of one generation and that of the next. It will be seen 

 that the total of this column (four generations) is 365.6 days, or 

 approximately one year. 



Table XXI. — Summary by stages of the length of each generation of normal individuals 

 of the dock false-worm, Wenatchee, Wash., 1915. 





Average number of days— 



Total 



life cycle 

 in days. 



Average 

 number of 



Generation. 



In egg 

 stage. 



In larval 

 stage. 



In pupal 

 stage. 



From 

 emergence 

 to oviposi- 



tion. 



days from 

 egg deposi- 

 tion to egg 

 deposition. 



First .' 



10.7 

 4.8 

 4.7 

 3.8 



35.6 



21.3 



17.6 



233.0 



5.6 

 5.3 



4.7 

 10.5 



1.7 

 1.5 



1.9 

 2.9 



51.9 



31.4 



27.0 



247.3 



53.6 





32.9 



Third 



28.9 



Fourth 



250.2 







Total 













365.6 

















The seasonal history of the dock false-worm is shown in the dia- 

 gram in figure 6. In order to avoid crowding, only three points in 

 the life history are shown for each generation, namely, the hatching 

 of the eggs, pupation, and the emergence of the adults. Oviposition 

 would come a day or two later than the adult emergence. 



ABNORMAL NUMBER OF LARVAL MOLTS. 



We have seen that normally the dock false-worm molts five times, 

 and that consequently there are six instars in the larval stage. It 

 seems certain that occasionally, however, there are seven larval 



