SEASONAL HISTOEY. 



37 



Table XIII. — Percentage of hibernating larvm of the grape root-worm as found in 

 vineyards during the fall of 1909 at North East, Pa. 



Curtis vineyard, in 

 the valley. 



Algren vineyard, in 

 the valley. 



Young vineyard, on 

 the hill. 



Date of 

 digging. 



Percent- 

 age of 

 larvae 



in cells. 



Date of 

 digging. 



Percent- 

 age of 

 larvse 



in cells. 



Date of 

 digging. 



Percent- 

 age of 

 larvse 



in cells. 



Oct. 5.-.- 

 Oct. 12. . . 

 Oct. 19. . . 

 Oct. 28. . - 



5 

 20 

 12 

 83 



Oct. 4...- 

 Oct. 14... 

 Oct. 19... 

 Oct. 25. . - 





 

 14 

 36 



Oct. 12... 

 Oct. 20... 

 Oct. 28... 

 Nov. 12.. 





 3 

 16 

 33 



SPRING FEEDING OF THE LARVA. 



In the spring, with normally developed larvse, comparatively 

 little feeding takes place. In the early part of May, 1909, the 

 larvse in the rearing cages were still in their wintering cells, and 

 the condition in the field in most places did not permit the larvse to 

 become active previous to that time. Since occasional pupal cells 

 were found on May 24 in the field (Table XIV) and continued to 

 appear in rapidly increasing numbers, the time of spring feeding 

 may, on an average, have lasted 20 to 25 days. 



Table XIV. — Appearance of larvse of the grape root-worm in cells previous to pupation 



at North East, Pa., 1909. 



Date of 

 digging. 



Soil 

 condition. 



Total 

 number 

 of larvae. 



Number 

 of larvse 

 in cells. 



Percent- 

 age of 



larvae 

 in cells. 



May 19... 

 May 24. . . 

 May 25. . . 



May 2Q. '. '. 

 May 27. . . 

 May 29. . . 



June 1 



June 2. . . 

 June 3 . . . 

 June 4 . . . 



Gravel 



Sandy 



do 



Loam 



Gravel 



Clay 



Silt 



Clay 



Gravel 



Silt 



Gravel 



230 

 35 



140 

 33 

 32 

 47 

 79 

 6 

 7 



63 

 54 







3 

 37 



7 



2 



4 



23 



8.6 

 2.8 



21.2 

 6.2 

 8.5 



29.1 



2 



25 

 10 



2.8 

 39.0 

 18.5 



TIME AND MAKING OF THE PUPAL CELL. 



The pupal cells are found from 2 to 3 inches below the surface of 

 the ground. Like the wintering cells, they are made by a peculiar 

 rolling and twisting motion of the larva, whereby the cavity is 

 enlarged, the earth becomes packed together, and the inside smoothly 

 finished. The cell is quite spacious and would readily accommodate 

 a larva twice the size of the owner. Usually 15 days are required to 

 complete the pupal cell. As recorded in Table XVI, the average 

 length of time spent by the larvse in the cell is 21 days, which includes 

 the post-larval stage described below. Should the cell be disturbed 



