558 EXPERIMENT STATION RECORD. 



in practically all of the vine-growing sections, but is most injurious in the 

 Sacramento and San Joaquin valleys. Another species (Tcttcgonia utropunc- 

 tata) is frequently injurious in the coast valleys. 



" The hoppers pass the winter as adult insects on a wide range of food plants 

 that may be growing in the vineyard or vicinity. 



" They attack the vine as soon as the foliage appears, and here they remain 

 until the leaves fall in the autumn. 



" One month after they begin feeding on the vine, the overwintering hoppers 

 begin egg laying, which is continued over a period of a month or two, after 

 which they die. The hoppers of the spring brood arising from eggs laid in 

 May, become full grown in 3 weeks, begin egg laying 2 or 3 weeks later, and die 

 off In August or September, making the life of this spring brood approximately 

 3 or 4 months. Hoppers arising from eggs laid by the spring brood in June 

 and later, remain on the vine until the leaves fall in autumn. They then take 

 to whatever succulent vegetation may be present in the neighborhood, where 

 they live over winter and attack the vines again in the following spring. These 

 begin depositing eggs a month after the leaves appear on the vine, and die off 

 in midsummer, making the length of this life cycle approximately 1 year in the 

 central valleys of California. 



" The most satisfactory control method tried during the past 2 years was the 

 use of the screen cage. This was found to capture about 85 to 95 per cent of 

 the adult hoppers at a time in the spring before any eggs are deposited. 



" Spraying for the nymphs about June 1, or just before the spring brood 

 becomes mature, will kill a satisfactory percentage of the nymphs or young, 

 but will not kill many adults, or prevent eggs, which are present at this time, 

 from hatching later. . . . 



" Plowing or other farm practices can not be relied upon, hut when such 

 measures are generally practiced throughout a neighborhood, they may aid in 

 reducing the numbers somewhat." 



A bibliographical list is appended. 



The California grape root- worm, H. J. Quayle {Calif ornia St a. Bui. 195, 

 pp. 26, figs. J 8). — Ado-cus obscurus has been a destructive enemy of the vine in 

 Euroi)e for many years, but while known to attack the leaves of the grape in 

 California for a number of years only with the past year or two has it been 

 known as a root feeder. As the life history and habits of this species are 

 almost identical with the grape root-worm {Fidia inticida) of the Eastern 

 States and since it is a great pest only in California, the common name '" Cali- 

 fornia grape I'oot-worm " has been applied. 



From June to May the insect is in its larval and pupal stages under ground, 

 while during May and June it works on the parts of the vine above ground as 

 a beetle. The eggs are laid in clusters of from 4 to 30 usually in crevices 

 between the inner layers of the bark on old wood, as many as 79 eggs having 

 been obtained from a single female. In breeding experiments eggs hatched in 

 from 8 to 12 days. Upon emerging the larv;ie make their way into the groimd 

 almost immediately, where they commence feeding, usually upon smaller root- 

 lets at first which may be eaten entirely off. The larger roots are injured by 

 their gouging out long strips of bark, and in cases of severe injury all the bark 

 may be eaten away. Feeding is continued from the time they hatch in the 

 spring until the vine becomes dormant in the fall. Some of the larvje were 

 found nearly full gro-mi by September 1, while others were only half grown, 

 the latter completing their growth in the spring. The larvse were found as far 

 down as 2i ft. The full-grown larvie which winter over in the ground change 

 to pup;Te in the early spring, ascending to within 4 to 8 in. of the surface before 

 pupating. Two weeks are required for development in the pupal stage. 



