112 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



the vine. In the vines thus infested, all the leaves within a radius of 

 a foot or two from the center of the vine have dried up and many have 

 fallen off by the end of June or July, thus exposing the fruit. This 

 early loss of foliage prevents the berries from maturing properly. The 

 sugar content of the grape is much reduced, and in table varieties the 

 characteristic coloring, which is important, is not attained. In addition, 

 the fruit is badly soiled by the excrement of the hoppers which serves 

 to hold dust and dirt or offers suitable conditions for the growth of 

 fungi and often this covers the leaves so thoroughly as to interfere 

 with respiration. The loss of leaves, or any interference with their 

 normal functions, also prevents the proper ripening of the canes for the 

 next year's wood, and thus the vine may require a year or more to 

 recover from severe cases of hopper injury. 



This insect is not more than a tenth of an inch long and of a pale 

 yellow color, prettily marked with irregular red markings. 

 They are usually found on the under side of the leaves, 

 and if these are turned over carefully the insects may be 

 seen. They are very readily disturbed, and often emerge 

 from a vine in swarms, so that they are not likely to be 

 mistaken for any other insect pest of the vineyard. 



Life History. The life history of this insect as it has 

 FIG. 3. The been worked out in this State during the past year is, 



grape leaf- . 



hopper. briefly, as follows: 



Hoppers which have reached full growth on the vine during 

 the fall or late summer remain in the vineyard or vicinity during 

 the winter season. During the colder days they are more or 

 less dormant and will be found hiding under the leaves, or other 

 rubbish in the vineyard, or sheltered in the vegetation along the 

 bordering fences or roadsides. 



During the warmer days of winter they become fairly active and will 

 be found feeding on whatever vegetation happens to be growing among 

 the vines or in the vicinity. 



As soon as the vines come into leaf in the spring, they leave their 

 more varied food-plants of winter and attack the vine exclusively. 

 After feeding upon the grape foliage for about a month, egg-laying 

 begins. This in the Lodi section during the past season was about May 

 first. The eggs are laid just beneath the epidermis, on the lower side 

 of the leaf, rarely on the upper surface. They may be distributed any- 

 where over the surface and are most difficult to see unless one is famil- 

 iar with their appearance. We have counted more than seven hundred 

 of these eggs in a single leaf. One hopper will lay, on an average, 

 seventy-five to one hundred eggs, during a period of from one to two 

 months. The eggs from these over-wintering hoppers require about 



