1298 



THE FRUIT INDUSTRY IN NEW YORK STATE 



FIG. 437. LARVA OF GRAPE ROOT- WORM 

 (Enlarged) 



THE GRAPE ROOT-WORM 



The grape root-worm is the larva of a grayish-brown beetle 

 (Fidia viticida Walsh). This species is the most important in- 

 sect pest of grapes in !Xe\v 

 York. The larvae feed on 

 the fibrous rootlets and later 

 upon the bark and cambium 

 layer of the larger roots. 

 Vines showing roots with 

 the bark channeled, together 

 with an absence of small 

 fibrous roots (Fig. 436), 

 furnish almost conclusive 

 evidence of the work of this 

 pest, and when growers are 



not acquainted with the insect this root condition should be the 

 first sign sought in a diagnosis of the cause of weakened vines. 

 This feeding occurs during late summer and autumn, and during 

 that time the grubs usually 

 reach full growth (Fig. 

 437). Little feeding oc- 

 curs in the spring. During 

 June the grubs transform 

 to pupae and emerge as 

 adult beetles (Fig. 438) the 

 latter part of June or early 

 July. 



The feeding of the adults 

 produces characteristic 

 chainlike markings on the 

 upper side of the foliage 

 (Fig. 439). The feeding 

 is ravenous for the first few 

 days after emergence, but 

 diminishes with the in- 

 creased age of the adults. About two weeks after emergence, 

 egg^laying begins and continues for about one month, during 

 which time a female will lay about two hundred eggs. These 



FIG. 438. ADULT OF GRAPE ROOT-WORM 

 (Enlarged) 



