14 
THE GKAPE ROOT-WORM. 
the roots. In the breeding work, however, larvae were reared on 
wild grapevines, which shows that it is possible for the larva? to 
exist on these plants. In 1909 larvae hatching July 26 were placed 
in large earthen pots (fig. 22) in which, some time previously, wild 
grapevines had been planted. On examining the cages in the fall 
of the same year (1909) a number of larvae were found to have 
attained their normal growth, as compared with other larvae reared 
under similar conditions on cultivated vines. 
CHARACTER OF INJURY AND DESTRUCTIVENESS. 
The injury wrought by this pest on the grapevine occurs both 
above and below the surface of the ground ; however, by far the greater 
damage results from its work upon the roots. The injury above the 
ground is done by the beetles; that upon the roots by the grubs or 
larvae. 
The first intimation that the observant vineyardist is likely to 
obtain of the presence of this pest upon his vines is the appearance, 
late in June or early in July, of chainlike markings upon the upper 
surface of the foliage (PI. II). These markings are made by the 
beetle. Ordinarily this scoring of the leaves is not sufficient to 
materially affect the health of full-grown thrifty vines. Where the 
beetles are very numerous, however, and the foliage sparse, it not 
infrequently happens that the leaves are so badly scored that in a 
short time they take on a brown appearance and hang about in 
shreds. In the case of newly planted vines (fig. 29) extensive 
feeding by the beetles greatly retards the growth of the young plant 
and proves a great obstacle in the starting of a new vineyard. On 
the thick-leaved varieties of grapes, such as the Concord, Worden, 
and Niagara, this feeding does not extend through the heavy pubes- 
cence on the lower surface. The pubescence holds together only a 
short time, however, and soon either dries out or is torn apart by 
the growth of the leaf. On the thin-leaved varieties, as the Dela- 
ware, and on the wild species of grape, holes are eaten entirely 
through the leaf, usually assuming the characteristic chainlike irregu- 
larity of form. 
It is, however, to the larvae of this pest feeding upon the roots of 
the vines that the direct cause of the injury and death of so many 
vines is due. The work of the larvae upon the roots may be recog- 
nized, when the vines are removed from the soil, by the absence of 
root fibers, by channels along the larger roots, and by pittings on 
the main trunk. (See PI. III.) Vines that have become well 
established before the infestation by larvae will sometimes withstand 
the attack of a considerable number of grubs, especially if the soil 
is rich and has been well tilled. The evidence of continued heavy 
infestation is indicated by absence of fibers upon the whiplike roots 
