64 



Table XVIII. — Duration of larral indars. 



Food. 



Stage 

 I. 



Period of growth. 



Corn stems 



do 



do 



Rosebuds 



Corn silk 



do 



do 



Cotton 



do 



do 



Tobacco 



Cotton 



do ! 



do ! 



Miscellaneous . J 



Cotton ( 



Amarantus 1 



Tobacco ', 



Cowpeas | 



Cotton I 



Tobacco 



Tomatoes | 



Cotton 



do 



do 



do 



Cowpeas 



Cotton 



Average . . 



Apr.l-Mav9 



Apr.l0-May9... 

 Apr.l9-Mayl(j.. 

 May 15-June 3.. 

 June29-July 17. 

 July9-Julv25.. 

 July 19-Aug. 2 . . 

 July 19-Aug. 3 . . 

 July 29-Aug. 13. 

 July30-Aug.l6. 

 Aug. 4-Aug. 19 .. 

 Aug. 7-Aug.22 .. 

 Aug. 8-Aug. 24 . . 

 Aug.8-Aug.23.. 

 Aug. 8-Sept. 6 . . . 

 Aug. 20-Sept. 8 . . 



do 



Aug. 20-Sept. 9 . . 

 Aug. 20-Sept. 1 . . 

 Aug.31-Sept.l8. 

 Aug. 31-Sept. 16 . 

 Aug. 31-Sept. 20 . 

 Aug. 31-Sept. 17 . 

 Sept.8-Sept.25.. 

 Sept.l6-Oct.5... 

 Sept.20-Oct. 20.. 

 Sept.28-Oct.21.. 

 Oct. 13-Dec. 20 . . 



Stage 

 II. 



Sta:ge 

 III. 



17 



Stage 

 IV. 



Stage St^age ^ ^^^^^ 



22 



4 4 

 19 6 



21 !(a) 



7 



5 

 23 



2 



23 





37 1 12 



24 ! 6 



3 I 17 

 13 

 18 



2 



2 



4 i 8 



2 1 23 

 17 

 14 



4 2 



4 7 



7 13 



5 



8 



7 



2 



5 



5 



4 



4 



4 



4 



27 11 



29 I 5 



17 I 8 



16 ' 17 



Is 



15 



16 I 13 i 



22 

 21 

 17 

 18 

 10 

 10 

 23 

 17 

 15 

 22 

 23 

 17 

 6| 

 16 i 



! 



1 I 

 1 I 



19 I 

 3 I 



810 

 440 

 677 

 871 

 668 

 656 

 532 

 657 

 682 

 632 

 547 

 566 

 525 

 520 

 1,033 

 681 

 737 

 802 

 478 

 735 

 656 

 70> 

 646 

 429 

 687 

 960 

 637 



c-643 



a Omitted. 



b Not recorded. 



c In this average Nos. 15 and 28 are omitted. 



In the last column are given the sums of effective temperature 

 (above 43^) to which the larvae were subjected. While the range ^' 

 (429^-871°) is great, an average of 617^ does not fall far from most of 

 the records. 



The following table shows the average length of the different instars 

 for larvae feeding on corn and cotton : 



Table XIX. — Average length of larval instars for larvx fed on corn and cotton. 



Instar. 



Days. 



Hours. 



I . 



II . 

 III. 



IV . 



V . 



VI . 





3 

 3 

 2 

 3 

 3 

 4 



13 



I? 







1 













Total 



20 



18 





GROWTH DURING THE LARVAL INSTARS. 



The comparative rate of growth during the respective larval instars 

 is of interest as indicating the periods of most vigorous feeding, and, 



« Only rearings on corn and cotton are here considered. 



