34 



THE GEAPE EOOT-WORM. 



Table IX. — Incubation period of eggs of the grape root-worm as observed in 1909 at 



North East, Pa. • 



No. of 



Date. 





No. of 



Date. 





obser- 

 va- 





Days. 



obser- 

 va- 





Days. 











tion. 



Laid. 



Hatched. 





tion. 



Laid. 



Hatched. 





1 



July 15 



July 29 



14 



49 



Aug. 7 



Aug. 23 



16 



2 



...do.... 



July 30 



15 



50 



Aug. 8 



Aug. 20 



12 



3 



July 16 



...do.... 



14 



51 



...do.... 



Aug. 21 



13 



4 



July 18 



July 31 



13 



52 



...do.... 



Aug. 22 



14 



5 



...do.... 



Aug. 1 



14 



53 



...do.... 



Aug. 23 



15 



6 



July 19 



...do.... 



13 



54 



...do.... 



Aug. 24 



16 



7 



July 20 



...do.... 



12 



55 



Aug. 9 



...do.... 



15 



8 



...do.... 



Aug. 2 



13 



56 



...do.... 



Aug. 25 



16 



9 



July 21 



...do.-.. 



12 



57 



Aug. 10 



...do.... 



15 



10 



...do.... 



Aug. 3 



13 



58 



...do 



Aug. 26 



16 



11 



July 22 



Aug. 2 



11 



59 



...do.... 



Aug. 27 



17 



12 



...do.... 



Aug. 3 



12 



60 



Aug. 14 



Aug. 26 



12 



13 



July 23 



Aug. 4 



12 



61 



...do.... 



Aug. 27 



13 



14 



July 25 



Aug. 6 



12 



62 



...do.... 



Aug. 28 



14 



15 



July 26 



...do.... 



11 



63 



...do.... 



Aug. 29 



15 



16 



...do.... 



Aug. 7 



12 



64 



...do.... 



Aug. 31 



17 



17 



July 27 



...do.... 



11 



65 



Aug. 16 



...do.... 



15 



18 



July 28 



Aug. 8 



11 



66 



...do.... 



.X.'. 



16 



19 



July 29 



...do.... 



10 



67 



Aug. 17 



15 



20 



...do.... 



Aug. 9 



11 



68 



...do.... 



Sept. 2 



16 



21 



...do.... 



Aug. 10 



12 



69 



...do.... 



Sept. 4 



18 



22 



July 30 



Aug. 9 



10 



70 



...do.... 



Sept. 5 



19 



23 



...do.... 



Aug. 10 



11 



71 



Aug. 18 



Sept. 4 



17 



24 



...do.... 



Aug. 11 



12 



72 



...do.... 



Sept. 5 



18 



25 



...do.... 



Aug. 12 



13 



73 



...do.... 



Sept. 6 



19 



26 



July 31 



Aug. 11 



11 



74 



...do.... 



Sept. 7 



20 



27 



...do.... 



Aug. 12 



12 



75 



...do.... 



Sept. 10 



23 



28 



Aug. 1 



...do.... 



11 



76 



Aug. 19 



Sept. 3 



25 



29 



...do.... 



Aug. 13 



12 



77 



...do.... 



Sept. 4 



16 



30 



Aug. 2 



...do.... 



11 



78 



...do.... 



Sept. 6 



18 



31 



Aug. 3 



...do.... 



10 



79 



...do.... 



Sept. 7 



19 



32 



...do.... 



Aug. 14 



11 



80 



...do.... 



Sept. 8 



20 



33 



...do.... 



Aug. 15 



12 



81 



...do.... 



Sept. 9 



21 



34 



...do.... 



Aug. 16 



13 



82 



...do.... 



Sept. 10 



22 



35 



Aug. 4 



Aug. 17 



13 



83 



...do.... 



Sept. 11 



23 



36 



Aug. 5 



Aug. 16 



11 



84 



...do.... 



Sept. 12 



24 



37 



...do.... 



Aug. 17 



12 



85 



Aug. 20 



Sept. 6 



17 



38 



...do.... 



Aug. 18 



13 



86 



...do.... 



Sept. 7 



18 



39 



...do.... 



Aug. 19 



14 



87 



...do.... 



Sept. 8 



19 



40 



Aug. 6 



Aug. 18 



12 



88 



...do.... 



Sept. 9 



20 



41 



...do.... 



Aug. 19 



13 



89 



Aug. 26 



Sept. 18 



23 



42 



...do.... 



Aug. 20 



14 



90 



...do.... 



Sept. 19 



24 



43 



...do.... 



Aug. 21 



15 



91 



Sept. 3 



Sterile. 





44 



Aug. 7 



Aug. 18 



11 



92 



Sept. 10 



Sterile. 





45 



...do.... 



Aug. 19 



12 



93 



Sept. 12 



Sterile. 





4fi 



...do.... 



Aug. 20 



13 



94 



Sept. 13 



Sterile. 





47 



...do.... 



Aug. 21 



14 



95 



Sept. 14 



Stsrile. 





48 



...do.... 



Aug. 22 



15 



96 



Sept. 20 



Sterile. 





Table X. — Summary of Table IX; time of incubation of grape root-worm eggs for 1909. 



Incubation. 



Average. 



Maximum. 



Minimum. 



For the entire egg period 



Days. 

 14.67 

 12.3 



Days. 

 24 

 16 



Days. 

 10 

 10 



For the maximum egg period, July 22-Aug. 8, inclusive 



Eggs laid at approximately the same date by the same female 

 varied in the time of hatching to the extent of several days. The 

 embryological development becomes particularly prolonged later in 

 the season with the advent of colder weather. All the eggs laid dur- 

 ing the month of September failed to hatch. 



The rate of hatching of eggs in the field has been recorded in 

 Table XI. 



