22 BULLETIN 903, IT. S. DEPARTMENT OF AGRICULTTTRE. 
appearance to the vines. Scarcity of rapid-growing terminal shoots 
and absence of tendrils are characteristics of stunted vines. Plate 
I, figure 1, shows a young vineyard which is uninfested and in which 
the vines have made normal growth. Plate II shows a small phyl- 
loxera " spot " in an old vineyard, the photograph showing stunted 
vines in the foreground. Plate III and Plate I, figure 2, indicate 
badly infested old vineyards, in which all the vines are phylloxe- 
rated and most of them badly stunted. The vine in the foreground 
of Plate III is obviously stunted, although less so than its neighbors. 
PHYLLOXERA ROOT LESIONS. 
Root lesions are swellings on grape roots caused by the puncture 
of the phylloxera beak. They are of two types, (1) nodosities and 
(2) tuberosities. 
The nodosity. — Nodosities (PL IV, fig. 1) are rapidly growing 
swellings on the white fleshy feeding rootlets. They soon acquire 
a characteristic greenish-yellow color, and curve and bulge around 
the phylloxeras responsible for their inception so that the insects 
come to lie in a depression (PL IV, fig. 1, b). A nodosity may be- 
come as much as six times the diameter of the normal size of the root 
when several insects have settled upon it, and about twice the di- 
ameter for a single occupant. Through its size, form, and color, 
the nodosity is very conspicuous in comparison with the root and is 
manifest proof of the presence of the phylloxera. 
In most cases the formation of a nodosity arrests the growth of the 
rootlet. At times the rootlet grows one-fourth inch or so in length, 
and occasionally the puncture of the phylloxera does not affect the 
rootlet in its growth, the subsequent swelling acquiring a lignous 
character and becoming a tuberosity. Nodosities are generally short- 
lived, lasting about a month. Excess moisture hastens their decay, 
lack of moisture dries them up, but a low, even temperature causes 
them to last longer. 
The foregoing also applies to the American variety of vines styled 
nonresistant. On the rootlets of the resistant American vines the 
phylloxeras frequently fail to cause swellings, and when nodosities 
are produced they are smaller, less fleshy, and brown in color. At 
times, though no swelling occurs, the rootlet dies at the point of 
puncture. 
The tuberosity. — Tuberosities (PL IV, figs. 2, 4) also are swellings 
caused by the puncture of the aphid. Though of a similar nature, 
they differ from nodosities in form because of the lignous character 
of older roots. They occur on all parts of the root system of vinifera 
vines except at the apex of the growing fibrous rootlets. They may 
