6 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



known to occur in New York since 1866, and has been a pest on the vines 

 there since about 1893. 



This insect in all essential respects, so far as habits go, is similar to 

 the one treated of in this bulletin. It is also closely related entomolog- 

 ically, both being members of the same group (Emolpini) . The common 

 Diabrotica, the flea-beetles, the asparagus beetle, and numerous other 

 leaf eating beetles belong to this same family. 



Economic Importance. While the insect has occurred on vines in the 

 State for the last thirty years it seems not to have spread so > rapidly as 

 might have been expected, judging from the experience with the same 

 insect in Europe and its related species in the Eastern States. It is 

 difficult to explain just what may account for this. 



Since the greater part of the insect's life is spent in the ground, it is 

 in this stage that conditions would be most likely to influence its 

 progress. Such conditions might be found ' in the kind of soil, the 

 cultivation of the soil, the variety of vines and the great depth of the 

 root systems in some of our drier sections. Again, the true importance 

 of the insect's work has never been appreciated in the State hitherto, 

 since it has been known as a leaf feeder entirely. Vines, therefore, may 

 have shown a general unthriftiness due to its attacks, but because the 

 root infesting habits of the larvse were unknown the trouble may have 

 been assigned to other causes. 



However, during the present season in the neighborhood of Lodi, 

 we have good evidence of what injury the insect may bring about. In 

 the particular vineyard where our studies were made, it had been 

 noticed that something was wrong with the vines, but just what it was 

 had not been determined. During the past winter two or three acres 

 of the vines which were worst affected were dug up. The piece adjoin- 

 ing where these vines were uprooted was badly infested during the 

 past spring with a beetle with which the .owner (who came into posses- 

 sion of the property a year ago) was unfamiliar. The matter was 

 reported to us and upon investigations it was found to be the root beetle. 



The beetles were very abundant over a narrow strip in the center of 

 the vireyard and had already done considerable injury to the leaves 

 and other growing parts of the vines. The men who pruned the vineyard 

 in the winter noticed that this strip of vines had not made the growth 

 that was made by the vires on either side. Fortunately the old stumps 

 and roots which had been dug up had been saved for fuel, and upon 

 examination were found to be badly gnawed by this insect. Some of 

 the vines in the strip where the beetles were abundant this year made 

 practically no growth until late in the season. The beetles were nearly 

 all killed on this area this year, and hence the vines became free from 

 the larvae and started their growth very late. On another vineyard 



