252 



INJURIOUS INSECTS 



seen, and there is every reason to believe that he has no 

 existence. Nor does the female ever acquire wings. It 

 is but a transient summer state, not at all essential to 

 the perpetuation of the species, and does, compared with 

 the other type, but trilling damage. 



As already indicated, the autumnal individuals of gal- 

 licola descend to the roots, and there hibernate. There 

 is every reason to believe also that, throughout the sum- 



Fig. 154. GRAPE PHYLLOXERA, ROOT-INHABITING TYPE. 



a, Roots of Clinton vine, showing relation of Swellings to Leaf-galls, and power of 



resisting decomposition ; fc, Larva as it appears when hibernating; c, <J, 



Antenna and Leg of same ; e, /, q, Forms of more mature Lice ; 



h, Granulations of Skin ; i, Tubercle. 



mer, some of the young lice hatched in the galls are 

 passing on to the roots; as, considering their size, they 

 are great travellers, and show a strong disposition to 

 drop, their natural lightness enabling them thus to 

 reach the earth with ease and safety. At all events, we 

 know from experiment, that the young gallicola, if con- 

 fined to vines on which they do not normally form galls, 

 will, in the middle of summer, make themselves perfectly 

 at home on the roots. 



