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BULLETIN 903, U. S. DEPARTMENT OF AGRICULTURE. 
The part of the life cycle from the sexes to the gallicoles through 
the winter egg and fundatrix is either omitted or does not proceed 
beyond the winter egg in California, notwithstanding the frequent 
Fig. 5. — PJij/Uoxera ritifoliac: Genealogical graph of the grape phylloxera in California. 
A, hibernant radicicole ; B-G, successive radicicole generations ; H, winged sexuparous 
migrant ; I, sexes ; Z, emergence above ground of the wandering radicicole larvse. 
abundance of resistant types of vines, types many of which normally 
bear galls in other localities. The result is that the California cycle 
(fig. 5) is purely parthenogenetic and is therefore greatly modified 
from the original cycle (fig. -±) occurring on wild vines, the natural 
hosts of the insect. 
