THE GRAPE PHYLLOXERA IN CALIFORNIA. 77 
inch of soil, which was a silty loam mixed Avith heavier clay loam. 
In some half -darkened cages, containing potted vines, the nymphs 
were observed to ascend to the level of the soil surface to transform. 
On the other hand, occasional nymphs have been found to transform 
on the roots as much as several feet underground, and many of the 
resultant migrants failed to reach the surface of the soil. 
HABITS OF WINGED MIGRANTS. 
Occasionally it was noticed in the jars that migrants would thrust 
their beaks into the roots and appear to feed. While engaged thus 
they lower the head so as to allow the beak to penetrate the tissues 
of the root. This organ appears to issue from the mesosternum, 
because of the curvature of the sheath. The femora are kept hori- 
zontal, and the antennae are usually in motion. While the insect is 
walking the antennae are 'in motion. The migrants, so far as has 
been noted, never feed after they issue from the soil. At all times 
they exhibit strong positive phototropism. When placed in a room 
they seek to crawl toward windows, and their activity is greatly 
increased when placed in the direct sunlight. If placed in a petri 
dish in the sunlight, they travel very fast and often take to flight, 
and are capable of keeping up a walking gait for hours. If the 
surface upon which they are standing becomes heated, they quickly 
die. If a vine leaf or other shade-giving object is placed in the dish, 
the phylloxerae will finally settle on the shady side of the object. 
In the vineyard most of the winged phylloxeras were observed to 
issue from the soil by creeping up the stumps of the vine. On arriv- 
ing at the surface many of them passed to the soil and crawled 
around aimlessly. Others crawled up the vine, and when they 
reached a point of vantage, such as the end of a cane, they spread 
and vibrated their wings, as though inviting the wind to bear them 
off. Finally they launched themselves into the air and if they struck 
a wind current were borne off. Often after spreading their wings 
once or twice they turned about and crawled down the stalk, and 
frequently when they launched themselves into the air no current of 
wind caught them, and they half fell and half flew to the ground 
in an oblique direction, but at other times they flew off strongly 
without the aid of the wind. The migrants are capable of traveling 
by flight and with the wind, as is evidenced by the experiments con- 
ducted with sticky papers. (See Diffusion of phylloxera, p. 100.) 
They have been taken on such papers at least 80 feet from the near- 
est infested vine, and undoubtedly they may travel much farther. 
In order to ascertain whether the migrants returned to the soil by 
crawling down the stem of the vine, 26 migrants were placed on the 
upper foliage of a small American vine (9 inches in height), on 
