118 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



five to twenty-five or thirty. Hatching occurs in from eight to twelve 



days, when the young larva appears and crawls, or possibly drops, to 



the ground and makes its way to the roots. 



After having burrowed its way through the ground to the roots it 



begins feeding, probably mostly on the smaller roots at first, later 



attacking the larger ones and eat- 

 ing out strips of the bark. This 

 feeding continues until winter, 

 when the larva becomes dormant, 

 finally changing to the pupa in the 

 following spring. Pupation took 

 place this year during the last of 

 April, and continued well into June. 

 The first beetles emerged about the 

 first of May. 



The most serious injury to the 

 vine is due to the work of the larvae 



FIG. 7. Imported grape-root worm. ,1 ,1 n i 



on the roots, the small roots being 



eaten off entirely, thus preventing the plant foods, taken up directly 

 by the root hairs, from reaching the growing parts of the vine. The 

 larger roots are injured by having strips of the bark eaten off, in bad 

 cases of injury scarcely any of the bark being left. Vines thus affected 

 show a stunted condition, the canes failing to attain a normal growth, 

 and in severe cases the vines may be killed outright. 



Con trnl Measures. Since the insect comes to the surface and feeds 

 upon the leaves and other growing parts of the vine an opportunity is 

 offered for fighting it in this stage. The beetles are very readily jarred 

 from the vine and may be captured if something is placed under the 

 vines in which they can be caught. 



The hopper cage, described on page 114, checked the development of 

 the beetles in a vineyard near Lodi during the past season. This 

 means has the advantage of capturing the hoppers also, which are more 

 than likely to be present, at the same time. The fact that the beetles 

 keep emerging from the ground for a month or so may make more than 

 one operation necessary. Fortunately, however, the beetles are usually 

 confined to a limited area of the vineyard, so that it is not necessary to 

 go over a large area. When the beetles alone are to be caught, simply 

 the tray on the bottom of the cage can be used. Handles may be 

 attached directly to the tray for convenience in manipulating. 



These beetles may also be fairly well controlled by an arsenical 

 spray. They are rather resistant to poisons and a strong dose must be 

 used. We obtained fairly satisfactory results by using lead arsenate 

 in the ratio of five pounds to fifty gallons of water. Paris green may 



