BEETLES RELATED TO GRAPE ROOT-WORM BEETLES. 



15 



(Pi. rV, fig. 2, in comparison with fig. 1) extending from the main 

 root a distance of several feet. The extremities of such roots are 

 frequently dead and in a decaying condition, and the portion near 

 the stem is mucti channeled and pitted by the feeding of the larger 

 larvae (PI. III). The life of such vines during this infestation has 

 been sustained by the throwing out of new fibrous roots either at 

 the crown or from the large lateral roots at a short distance from the 

 base of the vine. If the number of larvae increases sufficiently to 

 eat off these new fibers, the whole vine declines quite rapidly, and the 

 effect of the attack is readily recognized by a sickly stunted growth 

 of vine and undersized clusters of fruit, and in extreme cases by the 

 early shedding of foliage and actual shriveling of fruit before the 

 ripening period. 



BEETLES RELATED TO THE GRAPE ROOT-WORM BEETLE. 



The grape root-worm is a member of the large group of leaf-eating 

 beetles known as the Chrysomelidse. To this family belong the 

 common Colorado potato beetle 

 (Leptinotarsa decemlineata Say), 

 the elm leaf -beetle (Galerucella lu- 

 teola MiilL), the asparagus beetle 

 (Crioceris asparagi L.), several 

 important pests of the genus 

 Diabrotica, the grapevine flea- 

 beetle (Haltica cJialyhea 111.), and 

 many other injurious beetles. 



Closely related to Fidia viti- 

 cida Walsh (fig. 10) is the Cali- 

 fornia grape root-worm {Adoxus 

 ohscurus L.) (fig. 2), of which 

 there are two varieties, namely, 

 a black form, known as A. ohscu- 

 rus, and a bicolored form, known 

 as A. ohscurus vitis. Both vari- 

 eties occur in this country and 

 have been reported from sev- 

 eral widely separated States and 

 from Canada. It is found generally in Europe and throughout 

 Siberia. At present it is becoming injurious to vineyards in Cali- 

 fornia, infesting the European varieties of the cultivated grape. A 

 valuable contribution to the knowledge of this insect was published 

 by Mr. II. J. Quayle ^ in 1908. In habits this beetle is in most 

 respects similar to the eastern grape root-worm, Fidia viticida, and 

 the two pests can thus be combated with similar methods. It will, 

 however, be necessary to take into consideration the local conditions 



Fig. 2. — The California grape root-worm {Adoxus 

 obscurus): Adult or beetle. Much enlarged. 

 (Original.) 



«BuL 195, Cal. Agr. Exp. Sta., 190$, 



