﻿STKAWBERRY EOOTWORM ON GREENHOUSE EOSES 



23 



iDed from plant to plant is indicated by the fact that when confined in 

 pill boxes or cages with soil they pulverized the earth very thor- 

 oiichlv. 



Very little is known regarding the number of molts and the time 

 of molting. One larva which was 4 days old was seen freeing itself 

 from the "old skin. This was probably the first molt, but nothing 

 further Avas noted. 



DURATION OF THE LARV-\L STAGE 



From an examination of Table 11 it will be seen that the duration 

 of the larval period is from 33 to 74 days. Seasonal conditions, as 

 well as moisture and temperature, undoubtedly affrct the length of 

 this stage. In cases where the date of pupation was not noted, the 

 duration of the larval period was calculated by deducting 8 to 11 

 days, the time usually required for the pupal stage, from the num- 

 ber of days between hatching and the emergence of the adult. 



Table 11. — Duration of larval and pupal stages of the straioTjerry rootworm-, 



1920, 1921, and 1922 



[Observations taken at Doylestown, Pa., except those on June 11, 12, and 14, 1922, which were taken at 



Washington, D. C] 



Num- 



Date of— 



Duration of stages 





ber of 

 indi- 

 viduals 



Hatching 



Pupation 



Emer- 

 gence 



Larva 



Pupa 



Larva 

 and 

 pupa 



Remarks 



1.. 



2 



2 



4 .. 



4 



1 



1920 



Mar. 24 



24 



June 3 and 4..-. 

 3 and4..-- 

 3 and 4..-- 



1921 

 May 2 - 



1920 



June 4 



6 



Aug. 1 



lto5 

 1 to5 



1921 



1920 

 June 16- 



18. 



Aug. 14- 



16- 



18 



1921 

 June 29. 

 July 12- 



12. 



15. 

 Aug. 15. 



14. 



1922 

 June 15. 

 27. 

 30. 



Days 

 72 



74 

 58 to 59 

 58 to 63 

 58 to 63 



Days 



12 



12 



13 



11 to 15 



13 to 17 



Days 



84 



86 



71 to 72 



73 to 74 



75 to 76 



58 



Pupation not observed. 



4 





July 1.... 

 2-..- 

 7.... 



Aug. 4 



5...- 



1922 

 June 5 





11 

 10 



8 

 11 



9 



10 



Hatching not observed. 



2 





Do. 









Do. 



2. 





Do. 



2 









52 "to 58 

 55 to 61 



Do. 



I. 



1922 





Do. 



3 



Apr. 30 to May 6 

 30 to May 6 

 May 11 . . 





Pupation not observed. 



1 







Do. 



2 



July 5. . 



55 

 54 

 49 

 47 





Died before emergence. 



2 



26 



19.... 

 15 



July 27. 



8 



62 





1 



27 . 



Do. 



1 



29 



15 









Do. 



1 



31 





July 27. 



29. 



Aug. 1. 



7. 





57 

 56 

 55 

 61 



44' 



43 

 41 



Pupation not observed. 



3 



June 3 







Do. 



1 



7 



July 27.... 



27-... 



Aug. 16 



50 1 5 

 50 ' 11 



54 1..-. 





1 



7 





2 



23 



Died before cuiorgeiito. 



1 



11 





July 25. 



25. 

 25. 



Pupal stage estimated 



2 



•12 







as 8 to 11 days. 

 Do. 





14 









Do. 













Days 



AveranclenKth of larval stage (based on 23 specimens) 58 



.\Iaxi Ilium Iriii^iii of larval stage 74 



Minimum lenk'th of larval stage ^ — 47 



Minimum Umnih of larval stage (estimated) .• 33 



Average length of pii[)al stage (based on 33 specimens) 10.9 



Maximiun length of jiupal stage 17 



Minimum length of pupal stage 5 



