16 



UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



The Beetle. The adult beetle, into which the pupa in its cell in the 

 ground transforms, emerges from the ground and begins to attack the 

 growing parts of the vine above ground. For the greater part of the 

 season the insect has been a root feeder, but having completed its early 

 stages underground, it comes to the surface to feed for a brief time, 

 to lay its eggs, and then dies. The beetle as it comes from the ground 

 is somewhat lighter in color, but upon exposure to sun and light its 



chitinous covering 

 soon becomes darker 

 in color and more 

 rigid in texture. 



The time of ap- 

 pearance of the first 

 beetles during the 

 years 1907 and 1908 

 at Lodi was May 

 1st. They may con- 

 tinue to emerge 

 until June 1st and 

 possibly later, al- 

 though the greater 

 number of the beetles 

 came out in 1907 

 and 1908 during 

 the first half of 

 May. It has been 

 stated that a few 

 larvae and pupae 

 were taken on May 

 29th, which would 

 indicate that a few 

 belated beetles may 

 not appear before 

 the middle of June. 



FIG. 12. A cluster of grapes badly gnawed by the root beetle. 



The beetles were most numerous on the vines this season about the 

 middle of May. In the latter part of May they begin to disappear 

 and by the last of June are practically all gone. 



The beetles soon begin their work on the vine by feeding upon the 

 leaves. They are nearly always found on the upper surface. In feed- 

 ing they eat out chain-like strips from the leaves (Fig. 10), these slits 

 being about one twentieth of an inch wide and from a quarter to three 

 quarters of an inch long. Sometimes the framework of the tissues is 

 left, making a skeletonized effect, though often the entire substance is 



