784 



REPORT UNITED STATES GEOLOGICAL SURVEY, 



less, bypogeau mothers perform tbe very same function as the winged 

 ones ', i. c, tbey biy a few eggs, wbich are of two sizes, and which pro- 

 duce males and females, organized and constructed precisely as those 

 born of tbe winged females, and, like them, producing the solitary 

 impregnated egg. Thus, the interesting fact is established that even 

 tbe winged form is by no means essential to the perpetuation of 



tbe species; but that, if all 

 such winged individuals 

 were destroyed as fast as 

 they issue from the ground, 

 the species could still go on 

 multiplying in a vineyard 

 from } ear to year. We have, 

 therefore, tbe spectacle of an 

 underground insect, posses- 

 sing tbe power of continued 

 existence, even when con- 

 fined to its subterranean re- 

 treats. It spreads in tbe 

 wingless state from vine to 

 vine, and from vineyard to 

 vineyard, when these are ad- 

 jacent, either through pas- 

 sages in the ground itself 

 or over the surface ; at the 



Fig. M. — Type radicicola. a, roots of Cliutou vine, 

 showiug the relation of swellings to leaf-galls, 

 the power of resisting decomposition; h, larva, 



as it appears when hibernating; c, d, antenna same time it is able, in the 

 ana leg of the same ; efg, forms of more mature ^iuged Condition tO migrate 

 lico; /(, granulations ol skin ; i, tubercle; ;, trans- , ° , t <- 4. 



verse folds at border of joints; A-, simple eyes. ^® mucU more QlStaUt 



(After Riley.) ' points." — (Riley.) 



The solitary egg above referred to is the winter egg. As autumn ad- 

 vances, the winged individuals become more and more scarce, and only 



eggs, newly-batched larvae, 

 and a few wingless, egg-bear- 

 ing mothers are seen. Tbe 

 latter are said to die during 

 tbe winter, and consequently 

 the species in winter is repre- 

 sented by the larvae and a few 

 eggs. In spring the larvae molt 

 their winter coat, and, after 

 attaining maturity, lay eggs. 

 Tbe eggs laid by tbe winged 

 females are placed in thedown 

 of the leaf of the vine, but 

 more commonly in tbe earth 

 around the roots. 



As to remedies, one hun- 

 dred and forty have already 

 been proposed in France, but 

 none are infallible. The best 



r,^ ro rr 7. . , , 1 . . general remedyisflooding tbe 



Fig. 52. — T^v^ radicicola. «, 0, pupa andimago of a *'• if • 



problematic individual, orsupposed male ; c,rf, its '^^"^^'^["^ ^" autumu or WIU- 

 anteuna and leg ;e, vesicles found in the abdomen, ter. The best specific appli- 



( After Riley.) catiou has been found to be the 



bisulphide of carbon, two ounces to be placed in a bole near the root, the 

 earth becoming impregnated, the insects are killed. Mr. Hiley has urged 



