24 
THE GRAPE ROOT-WORM. 
first beetle emerged July 1, which shows a fairly uniform emergence 
of beetles in captivity as compared with their emergence in the field. 
The results of the emergence experiments are given in Table I. 
Table I. — Date of the emergence of S98 grape root-worm beetles (Fidia viticida) from 
the ground, as observed in the breeding cages in the spring and early part of the summer 
of 1909 at North East, Pa. 
Date. 
Number 
of beetles. 
Date. 
Number 
of beetles. 
Date. 
Number 
of beetles. 
July 1 
5 
July 9 
36 
July 17.... 
8 
July 2 
9 
July 10.... 
39 
July 18.... 
4 
July 3 
16 
July 11.... 
19 
July 19. . . . 
5 
July 4 
11 
July 12.... 
36 
July 20. . . . 
2 
July 5 
15 
July 13. . . . 
22 
July 22.... 
6 
July 6 
27 
July 14.... 
16 
July 23.... 
1 
July 7 
34 
July 15. . . . 
26 
July 24.... 
5 
July 8 
31 
July 16.... 
14 
July 25. . . . 
2 
Total . . 
148 
Total . . 
208 
Total . . 
33 
Date. 
July 27. 
July 29. 
July 30. 
Aug. 5. 
Aug. 9. 
Number 
of beetles. 
Total 
In figure 13 the curve shows more graphically the relative emer- 
gence of these beetles. It will be noted from this curve that after 
■gpi 
JULY i 2 
31 AUG 2 3 1 5 b 7 
Fig. 13.— Curve showing time and relative emergence of beetles of the grape root-worm from the 
ground in rearing cages at North East, Pa., 1909. (Original.) 
the first emergence the beetles continued to appear in rapidly increas- 
ing numbers, reaching a maximum July 10. The decrease in the 
number of beetles emerging after this date was more gradual, and 
emergence continued until late in the season. In the cages the last 
beetle emerged August 9, while in the field a single beetle was still 
found in the cell August 14. From July 1 to July 5, inclusive, 14.1 
per cent had emerged; from July 6 to July 16, 75.4 per cent had 
emerged; and the remaining 10.5 per cent emerged later. Thus the 
great majority of over 75 per cent emerged during a period of 10 days, 
and the maximum of emergence took place about 2 weeks after the 
first beetle had been observed in the field. 
