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AN INTRODUCTION TO ENTOMOLOGY 



Fig. 506. — Phylloxera, gall-inhabiting form: a, b, 

 newly hatched nymph, ventral and dorsal views ; c, 

 egg; d, section of gall; e, swelling of tendril; /, g, 

 h, mother gall-louse, lateral, dorsal, and ventral 

 views; i, her antenna; j, her two- jointed tarsus. 

 Natural sizes indicated at sides. (From Riley.) 



The sexuales . — 

 The eggs laid by the 

 winged migrants are 

 of two sizes ; from the 

 smaller eggs there 

 hatch males; and 

 from the larger eggs, 

 sexually perfect fe- 

 males. These pair 

 and each female pro- 

 duces a single egg, 

 which is laid in the fall 

 on old wood. Here it 

 remains over winter, 

 and from it in the fol- 

 lowing spring a stem- 

 mother is hatched. 

 This completes the 

 two-year life-cycle. 



Control. — Owing 

 to the great injury 

 that this species has 

 done to vineyards, 

 hundreds of memoirs have been published regarding it; but, as yet, 

 no satisfactory means of 

 destroying it that can be 

 generally used has been 

 discovered. Where the 

 soil conditions are favor- 

 able it can be destroyed 

 by the use of carbon-bi- 

 sulphide, but this is an 

 expensive method ; where 

 the vineyards are so situ- 

 ated that they can be 

 submerged with water at 

 certain seasons of the 

 year, the insect can be 

 drowned ; and it has been 

 found that vines growing 

 in very sandy soil are less 

 liable to be seriously in- 

 jured by this pest. 



While it is usually im- 

 practicable to destroy 

 this pest in an infested 

 vineyard, there is a pre- 

 ventative measure that 

 has given good results. 



Fig. 507. — Phylloxera, root-inhabiting form: a, 

 roots of Clinton vine showing the relation of 

 swellings to leaf -galls, and power of resisting de- 

 composition; b, nymph as it appears when 

 hibernating; c, d, antenna and leg of same; e, 

 f, g, forms of more matiu-e lice; h, granulations 

 of skin; i, tubercle; j, transverse folds at 

 border of joints; k, simple eyes. (From Riley.) 



