42 
THE GRAPE ROOT-WORM. 
limited to a very short period (see fig. 16). The first beetle in the 
field was observed July 11. In the spring of 1908, on collecting 
larvae in different vineyards two distinct sizes were found, as possibly 
due to climatic conditions of previous seasons. The larger larva? 
were full grown, while the smaller varied from one-third to three- 
fourths grown. In the rearing cages the full grown larvae trans- 
formed normally and without further feeding. Of the smaller larvae 
few matured at the normal time, many were quite belated, while quite 
a number wintered, thus spending two years as larvae in the ground. 
As a result of the early season of 1908 the beetles commenced to 
emerge by June 16. The emergence extended over a long period; 
JUNE 
15 20 25 J 
JULY 
0 5 /O /5 20 25 3 
AUG. 
0 5 /o /J 
J 
f 
1 
Trmrrrr 
Tm 
Wffnf 
M 
till 
If 
TnfflT 
Fig. 16. — Diagram showing variation in time of emergence of beetles of the grape root-worm during 
1907, 1908, and 1909 at North East, Pa. (Original. ) 
the latest beetles to emerge appeared in the rearing cages July 28. 
This longer emergence period was partly due to the delay in the 
development of larvae that hatched in 1907. In the spring of 1909 
the larvae were again of a more uniform size as a result of the long 
season of 1908, and the emergence in 1909, as recorded in figure 16, was 
about normal. On examining larvae in the field in the early fall of 
1909 data were obtained as to the prevailing number of 1-year and 
2-year old larvae (Table XIX). At the dates of these observations 
only a few of the new-brood larvae had attained one-half their growth 
while many of the eggs had not yet hatched, and since the 1908 brood 
larvae were full grown the two broods could then be readily told apart. 
