118 BULLETIN 903, U. S. DEPARTMENT OE AGRICULTURE. 
also to stand on the surface of the soil about its stem. Examination 
of the piece of severed root after the experiment was concluded 
showed that about 40 eggs and young had been washed off. Five of 
the adults suffered no injury from exposure nor did most of the 
remaining young and eggs. On July 12 the Catawba vine was found 
to bear a strong nodositous infestation. On June 6, for eight hours, 
two pieces of severed roots bearing a total of about 200 phylloxeras 
were subjected to a similar stream of water which subsequently flowed 
6 feet to a sound Mission vine. On the severed roots the majority 
of aphicls were not washed off. In this instance the roots of the living 
vine were not bared, and there were no cracks on the surface of the 
soil around it. On July 27 this vine was examined and found to be 
uninfested. The third experiment took place July 29. For eight 
hours two pieces of severed roots bearing a total of about 250 phyl- 
loxeras were subjected to a stream of water which subsequently flowed 
10 feet to a sound Feher Szagos vine growing in a pot. The surface 
soil in this pot had been previously watered, and thus was cracked. 
After the experiment was concluded, it was found that very few of the 
phylloxeras had been carried off the severed roots. September 16 the 
vine was examined, but it proved to be quite uninfested. In each of 
these three experiments a fine stream of water was used and the angle 
of declivity was slight. In the first experiment only, wherein the 
roots of the living vine were actually exposed to the stream of water, 
did an inoculation through water agency occur. It is evident, how- 
ever, that diffusion may occur by means of water-borne phylloxeras. 
In the California vineyards such a condition could arise normally 
only between November and May, for in the other months it is very 
rare to have rain in any abundance. In April and May, however, 
when the phylloxeras are active, heavy rains occasionally occur, and 
sometimes on the hillside vineyards deep waterways are formed, 
exposing the roots of vines to a depth of more than a foot. 
In this connection some laboratory experiments were made upon 
the resistance of eggs and larvas to water exposure. For this pur- 
pose small-sized glass vials and distilled water at about 64° F. were 
used. In one instance, in a corked vial, 9 out of 12 eggs hatched 
from 2 to 10 days after they were placed in the water. All those 
that hatched remained on the surface, while those that failed to 
hatch went to the bottom of the vial. In another instance eight 
recently deposited eggs were placed on the surface of the water in 
an uncorked vial. Six days later all had sunk to the bottom, but 
subsequently hatched. In a third experiment 11 well- advanced eggs 
were placed on the surface of the water in an uncorked vial. After 
11 days all the eggs had hatched, six having remained on the surface 
and five having sunk to the bottom. In all three experiments the 
hatched larvas failed to fasten to pieces of roots provided for them. 
