THE GRAPE PHYLLOXERA IN CALIFORNIA. 101 
feeding insects. This form generally occurred on resistant vines, 
but also on viniferse along with the sexuparous migrants. The indi- 
viduals exhibited much diversity in development, ranging from those 
with large wing pads to others bearing no vestige of wing pads, but 
having more fully developed eyes than the typical adult radicicoles. 
In nearly every case their eggs were parthenogenetic, the resultant 
larvae becoming root feeders. This form has been styled " inter- 
mediate," in that it is intermediate in structure between the radi- 
cicole and the winged form. Observations indicate that it occurs 
rather infrequently in California. It has been discussed under the 
heading " Nymphicals or intermediate forms" (p. 82). All the 
fully winged individuals observed in California which deposited eggs 
were sexuparous. 
To sum up, it is not believed that in California there is diffusion 
through the winged form. It is perhaps worth while to record 
some observations upon the behavior of the insects of this form in 
the vineyard. During July and August, 1914, these occurred in a 
Zinfandel vineyard badly infested with phylloxera. Previously 
roots of many of the vines on lighter soil had been dug up, and it 
had been found that a large production of migrants was developing, 
especially on vines having the external appearance of not being badly 
phylloxerated. The condition of the roots on this type indicated 
that phylloxeration had not been in progress more than two years 
and the tuberosities had not reached a stage of advanced decay ; but 
phylloxera? were abundant, and it was evident that another year 
would find the vines much less thrifty. Sticky paper, tacked to 
boards, was placed in the vineyards, both on the surface of the 
ground in a horizontal position and in a vertical position. The hori- 
zontal papers were placed beside infested vines at distances varying 
from 6 inches to 5 feet from the trunks. The vertical boards were 
placed throughout the infested part and outside of the vineyard 
and extended from the soil surface to a height of 7-§ feet. More 
winged migrants were obtained on horizontal boards than on the 
vertical boards in proportion to a given area of paper. The majority 
of migrants caught on the horizontal boards were found at the 
edges, indicating that they reached the papers by walking rather 
than by flight. In some cases where individuals were found in the 
middle of the sticky papers it appeared that these might have 
fallen down from canes of the vine above, but in many instances the 
phylloxera? obviously had reached the papers by flight or had been 
blown thither by the wind. Those on the vertical papers had either 
been borne by the wind or had flown voluntarily. On the vertical 
boards facing away from the prevailing wind no migrants were 
caught. Vertical boards with sticky paper were placed in the vine- 
yard on the following dates: June 20; July 7, 10, 13, 21, 24, 31; 
