58 



suckers. As soon as tlie ground thaws and the sap starts in the spring, these young lice 

 work off their winter coat, and, growing apace, commence to deposit eggs. All, without ex- 

 ception, become mothers, and assum3 the degraded form (a) already described. 



Fig. 4.5. 



Type Eadicicola :— n, shows a healthy root ; b, one on which the lice .are working, re- 

 presenting the knots and swellings caused by their punctures ; f , a root that has been 

 deserted by them, and where the rootlets have commenced to decay ; d, d, d, show 

 how the lice are found on the larger roots ; e, female pupa, dorsal view ; /, same, 

 ventral view ; ri, winged female, dorsal view ; A, same, ventral view ; i, magnified 

 antenna of winged insect ; j, side view of the wingless female, laying eggs on roots ; 

 A', shows how the punctures of the lice cause the larger roots to rot. 



" At this season of the year, with the exuberant juices of the plant, the swellings on the 

 roots are large and succulent, and the lice plump to repletion. One generation of the mother 

 form (a) follows another — fertility increasing with the increasing heat aud luxuriance of 

 summer — until at last the third or fourth has been reached before the winged form (b) 

 makes its appearance in the latter part of June or early in July. Such are the main fea- 

 tures which the development of the insect presents, to one who has studied it in the field as 

 well as in the closet. 



"Since I proved, in 1870 (adds Mr. Riley), the absolute identity of these two types by 

 showing that the gall-lice become root-lice, the fact has been repeatedly substantiated by dif- 

 ferent observers. Yet, strange to say, no one has heretofore succeeded in making gall lice of the 

 young hatched on the roots, though I formerly supposed that Signoret liad done so. It is, 

 therefore, with much satisfaction that I record the fact of having succeeded this winter in ob- 

 taining galls on a young Clinton vine from young rculkimla, and of thus establishing beyond 



