48 
THE GEAPE ROOT-WORM. 
these cages varied from 1 to 2\ inches, and were of a uniform height of 
20 inches. The two larger sides consisted of plate glass with outer 
wooden shutters on either side which could be removed for the exami- 
nation of the contents. 
The emergence records of Table I, as shown by curve in figure 
13, are the results of about 15 separate experiments with larvae 
transforming in large earthen pots filled with soil. Since the time 
of emergence of the beetles and their relative occurrence has a 
direct bearing upon the 
time of application of poison 
sprays against this pest, 
special attention and care 
were exercised in preparing 
these experiments. In the 
early spring approximately 
1,000 larvae were collected 
in different vineyards in the 
vicinity of North East, Pa. 
In many instances soil from 
different localities, which 
varied from loose sandy soils 
to heavy clay, was trans- 
ferred with the larvae to the 
rearing pots (fig. 2.2) . Pro- 
vision for the spring feeding 
of the larvae was made by 
planting young grapevines 
in the pots. Finally the 
pots were placed in the 
ground in the open field and 
were left undisturbed for the 
rest of the season. Before 
the beetles commenced to 
Fig. 22.— Earth en pot with wire-screen cover used in rear- appear wire Screen covers 
ing the grape root- worm. (Original.) were placed QVer each pot, 
so that a complete daily record could be kept of the number of 
beetles emerging from each separate pot. 
By preserving the beetles from the above-mentioned experiments, 
rearing material of known source and age was obtained for further 
experiments. The daily catch of beetles throughout the emergence 
period was transferred to so-called " stock jars," from which insects 
were taken as needed for miscellaneous experiments. The "stock 
jars" shown in the rearing shelter (fig. 18) consisted of large-sized 
glass jars covered with thin cloth. A layer of moist sand was placed 
