Bugs, Cicadas, Aphids, and Scale-insects 177 



ing region of any importance in France, or elsewhere, exempt from 

 phylloxera." 



Curiously enough this native American pest came to California, in which 

 state it has done much more damage than elsewhere in our country, from 

 France, introduced on imported cuttings or roots. It was first noticed about 

 1874; by 1880 vines had been killed by phylloxera in three counties and 

 hundreds of acres had been pulled up in the famous Sonoma Valley. 

 Since then the pest has spread, according to Bioletti, to all the important 

 grape-growing regions of central and northern California, and probably not 

 less than 30,000 acres of vineyards have been destroyed. 



The phylloxera appears normally in four forms: (i) the gall form, living 

 in little galls on the leaves, and capable of very rapid multiplication (this 

 form rarely appears in California); (2) the root form, which is derived from 

 individuals which migrate from the leaves to the roots, and which, by its 

 piercing of the roots, sucking the sap, and producing little quickly- de- 

 caying tubercles on the rootlets, does the serious injury; (3) the winged 

 form, which flies to new vines and vineyards and starts new colonies; and 

 finally (4) the sexual forms, male and female, which are the regenerat- 

 ing individuals, appearing after several agamic generations have been 

 produced. 



The life-history of the pest has been described as follows by Bioletti: 

 "Some time during the summer, usually in July or August, some of the eggs 

 laid by the root-insects develop into insects of slightly different form, called 

 nymphs. They are somewhat larger than the normal root form and show 

 slight protuberances on the sides, which finally develop into wings. These 

 are the winged or colonizing insects, which emerge from the soil and, though 

 possessing very weak powers of flight, are capable of sailing a short distance, 

 and if a wind is blowing may be taken many rods or even miles. Those 

 which reach a vine crawl to the under side of a leaf and deposit from three 

 to six eggs. These eggs are of two sizes, the smaller of which produce males 

 and the larger females. The female, after fertilization, migrates to the 

 rough bark of the two-year-old wood, where she deposits a single egg, called 

 the winter egg, which remains upon the vine until the following spring. 

 The insect which hatches from this egg in the spring goes either to the young 

 leaves and becomes a gall-maker, or descends to the roots and gives rise to 

 a new generation of egg-laying root-feeders. The normal and complete 

 life-cycle of the phylloxera appears then to be as follows: Male and female 

 insects (one generation in autumn); gall-insects (one to five generations 

 while the vines are in leaf) ; root-insects (an unknown number of genera- 

 tions throughout the year); nymphs, which become winged insects (one 

 generation in midsummer). The gall stage may be omitted, as it generally 

 is in California, and the insects which hatch from the fertilized eggs laid by 



