74 
THE GRAPE ROOT-WORM. 
observation, when the maximum number of eggs had been deposited, 
and before but few larvae had hatched from the earliest deposited 
eggs. 
All of the bark was carefully stripped from the vine and a count 
made of the egg clusters found. The number of eggs in these clusters 
may vary from 3 or 4 to 75 or even 100. Since it was impossible to 
make an actual count of the individual eggs, the clusters were classi- 
fied, as the count was made during the examination of the vines, as 
large when they contained approximately 50 eggs or more, medium 
when they contained about 30 eggs, and small when they contained 
about 10 eggs. In this manner we obtained the estimated number of 
eggs per vine given in the Table XXVI dealing with egg deposition. 
A simple enumeration of the number of egg clusters deposited per 
vine regardless of the number of eggs which they contained would 
have given but an inadequate idea of the total number of larvae which 
might infest the roots of these vines. The number of canes per vine 
is also given to indicate the size of the vine, since the limit of the area 
upon which the beetles could deposit eggs would have some influence 
on the number of clusters deposited. 
The prevalence of larvae at the roots of vines in sprayed and 
unsprayed plats was determined by making careful diggings at the 
roots of a given number of vines in both the sprayed and the 
unsprayed plats (Table XXVII). During these diggings the differ- 
ence in the number of root fibers thrown out by vines in the sprayed 
and unsprayed plats was very noticeable. On May 13, 1908, after 
the vineyard had received the protection of one season's treatment 
with poison spray the root systems of several vines were examined 
in the block of young Concords. It was found that the roots of 
many of the vines in the unsprayed plat were almost entirely devoid 
of new root fibers, and that the large roots were badly channeled and 
pitted by the feeding of the larvae of the grape root-worm, whereas 
the roots of vines examined in the sprayed portion of this vineyard 
showed that they had thrown out large masses of new fibrous roots 
during the growing season as a result of the protection the spraying 
had afforded them in the prevention of the deposition of eggs by the 
beetles. Plate IV, figure 1, will illustrate this luxuriant growth of 
new root fibers on roots of sprayed treated vines, practically all of 
which were produced during the growing season of 1907, as compared 
with the lack of them on the unsprayed vines (PI. IV, fig. 2). These 
illustrations also indicate the recuperative power of badly injured 
grape vines when protection from the larvae is afforded; for in the 
spring of 1907, previous to the protection of the vines by the poison 
spray, the roots of the vines in the sprayed plat were as devoid of 
root fibers as were those in the unsprayed plat, as was shown by dig- 
gings made in the spring of 1907. 
