KlG. 206. Phylloxera vastatrix. I. a, under surface of a leaf of an American grape vine, showing 

 galls ot Phylloxera ; b, upper surface of leaf showing entrances of galls ; c, exterior of gall enlarged ; 

 c/, gall in section with eggs; 2. a and b, rootlets of grape vines with swellings caused by the punc- 

 tures of the Phylloxera; 3, root of a diseased vine with hibernating colonies of apterous females 

 under the bark; 4, development of Phylloxera; a, egg laid by a winged female (c u ) on the wood 

 of the vine above ground, which develops into the apterous female, a u , containing a single egg ; a', 

 egg laid by c u , which develops into apterous male, a" 1 ; b, fertilized egg laid by a" under the bark 

 above ground ; from eggs of this sort only subterranean, apterous females develop, seen in b>, b", 

 b l,i , in successive stages of development; d' y , egg laid by b lu on the roots of the vine , 11 develops 

 parthenogenetically and a long series of parthenogenetic generations follows, but in the autumn 

 these eggs develop into pupae, c\ from which soon the winged females, c", emerge and lay their 

 eggs, a and a\ above ground; 5, map of France showing by the dark spots the distribution of 

 Phylloxera in 1877. (Photographed from a Leuckart-Xitsehe wall chart, by the author; permis- 

 sion of Dr. C. Chun.) 



