THE GRAPE PHYLLOXERA IN CALIFORNIA. 43 
On the Muscadine the phylloxera? upon hatching from the eggs 
refused to settle or feed. The nonresistant varieties were infested 
throughout summer and autumn, and on their roots the phylloxera? 
entered into hibernation from September 20 to the beginning of No- 
vember; in the case of the Champion, they hibernated as late as 
December 1. On the Catawba and Champion, the most heavily in- 
fested, the aphids began hibernation earlier; on the less infested 
Delaware, Isabella, and Lenoir, somewhat later. 
Aphids became active about the middle of February, and all 
hibernants were adult by April 13. This spring activity was some- 
what in advance of that occurring in vineyards, but was similar to 
that which occurred on the caged vinifera vines. On all nonresist- 
ant varieties it was observed that the hibernants massed on tuberosi- 
ties, nodosities, and the normal surface of the roots; and in cracks in 
a manner similar to that observed to occur on vinifera vines. 
On the resistant hybrids repeated inoculations during summer 
and autumn failed to produce more than an extremely light in- 
festation. The phylloxera? settled to hibernate during October, and 
at the end of that month all were hibernants. They were situated 
on side rootlets and on the normal surface of the root, but on the 
Rupestris St. George hibernants occurred also on nodosities which 
they had caused to form shortly after they settled. 
Hibernation on American vines in pots, 1912-1915. — A large series 
of 2-year-old vines (from cuttings) planted in 6-inch pots, originally 
used in resistance experiments and comprising resistant vines, we^e 
examined during the years 1912 and 1913 for hibernant observations. 
It was found that hibernation took place during the last half of 
October and first half of November and that the spring awakening 
proceeded from about March 10 to April 15. These vines were 
planted in light sandy soil. The hibernants settled chiefly on nodosi- 
ties and to a smaller extent on the surface of the larger rootlets. In 
the spring there was a great variation in the growth of the vines. In 
the majority of instances the phylloxera? on the early leafing vines 
molted sooner than those on the more backward plants. No tempera- 
ture records were kept with this series, but it is probable that the 
records taken 2 feet below the soil surface (Table XII) approxi- 
mated that which occurred in the pots in the winter of 1913-14. 
A further series (1914) of rooted vines in 9-inch pots, comprising 
Agawam, Isabella, Lenoir, Delaware, Catawba, and Champion, 
showed that with the exception of the Delaware, which was lightly 
infested, hibernation proceeded from about October 1 to November 
1, nearly all the insects being hibernants on the latter date. On the 
Delaware none of the phylloxera? were hibernants on October 30, 
and the roots were on that date still running strongly in sap, while 
the sap flow in the other varieties was weaker. The temperature in 
