GRAPE PESTS 
greenish-yellow in summer and a litile 
darker in winter. 
Life History 
During the months of July and August 
some of the eggs laid by the females of 
the root forms hatch into individuals 
which acquire wings. These seek the 
foliage of the vines and lay large eggs 
which produce true females and small 
eggs which produce males. These mate 
and each female lays a single winter egg 
upon the bark of the two-year-old wood. 
In the spring this egg hatches into a 
root form (or gall-making form) which 
gives rise to the root forms in other 
stages. These lay eggs which give rise 
to the many summer generations of de- 
vastating insects. In California the lat- 
ter hibernate in the soil and may con- 
tinue for at least four years without re- 
verting to the sexual forms. 
Food Plants 
This insect feeds upon practically all 
varieties of grape vines, but is most dam- 
aging to the European varieties. Many 
cultivated varieties and hybrids as well 
as wild species are slightly attacked, but 
not so as to greatly impair their growth. 
These latter are known as resistant vines 
and are important factors in the selection 
of roots for vines set out in Phylloxera- 
infested districts. While the leaves are 
damaged to some degree, the main source 
of injury is due to the attacks upon the 
young and vigorous roots, which are com- 
pletely destroyed. The roots of the so- 
called “resistant stock” do not material- 
ly suffer from such attacks. 
Control 
By far the most important method of 
control is the use of resistant root stocks 
upon which are grafted the desired vari- 
eties. Of course care must be exercised 
in selecting stock for the various vari- 
etics and expert advice obtained before 
making extensive selections or plantings. 
Direct remedies for infestations are un- 
satisfactory. Flooding the vineyards if 
the water can be held for a month will 
almost exterminate the pest, if done in 
the winter, but such a method is imprac- 
ticable in most of the grape-growing 
sections of the state. 
2—31 
1137 
Carbon bisulfid is an efficient remedy in 
loose sandy soil, but in such places the 
pest is usually less abundant. 
Natural Enemies 
In the Eastern states many predaceous 
insects feed upon the gall form, but as 
this stage does not occur to any extent 
in California there are practically no re- 
sults from these or other natural checks. 
E. O. Essic 
oR GRAPE VINE 
see Cal- 
GRAPE Roor Worm, 
Fivra. Fidia viticida Walsh. 
fornia Grape Root Worm. 
Grape Scale 
Aspidiotus (Diaspidiotus) uwvae Comst. 
This insect has a wide distribution 
over the eastern part of the United 
States and has proven of considerable im- 
portance. 
Infested vines have the appearance of 
being covered with a “dingy white 
scurf.” The habits of this scale are 
somewhat similar to those of the San 
Jose scale, but the grape seems to be its 
only host of economic importance. 
The female gives birth to living young, 
35 to 50 during May and June. These are 
active for about two days when they set- 
tle down to a sedentary life under cover 
of a waxy shield which they excrete. 
Spray with lime-sulphur once, about 
one week after the first appearance in 
the spring. Later applications are neces- 
sary sometimes. 
Reference 
Bureau of Entomology Bulletin 97, Pt. 
VII. 
Grape Seed Chalcis 
Hvozystoma vitis 
In the latter part of the summer 
grapes will sometimes shrivel and dry 
up. Examination of the seeds will find 
some of them missing and others en- 
larged. The swollen seeds may be found 
to contain a small white grub. This is 
the grub of the grape seed chalcis, 
which emerges, a wasp-like fly, some time 
the following summer. 
According to Gossard it prefers the 
wild grapes. 
Destruction of affected berries is all 
that is needed. 
