BULLETIN 198. 



THE GRAPE LEAF-HOPPER. 



185 



varied winter food plants. In 1908 an occasional hopper was found 

 on vines in the Sonoma Valley as early as March 18th. 



Do they Feed Exclusively on the Vine? Once they begin to feed 

 upon the vine they do not leave it for other food unless, of course, they 

 incidentally happen to find themselves in other situations. During 

 two or three weeks while the vine is 

 coming into foliage, some hoppers may 

 be found on the vine and others on 

 the winter food plants, but those that 

 are still feeding on the other vegeta- 

 tion have not yet found their way to 

 the vines. It. may be a couple of 

 weeks after the first foliage appears, 

 therefore, before all the hoppers will 

 be found on the vine ; but, once they 

 begin to feed on the grape, they remain until the vine becomes dormant 

 at the end of the season. 



Habits on the Vine. While the leaves are still expanding and not 

 yet affording much protection the hoppers will be found most commonly 



on the concave side of the leaves that 

 are not yet fully expanded, or on the 

 leaves near the base of the vine, where 

 they are not so completely exposed. 

 At this period they were not observed 

 to move about to any extent, and 

 seemed to be pretty well occupied 

 with feeding. 



Fig. 6. The two pairs of valves of the 

 ovipositor with which the insect 

 inserts its egg into the leaf tissues. 

 Greatly enlarged. 



Copulation and Oviposit ion. On 

 April 30, 1907, they were observed 

 pairing for the first time. This was 

 approximately three weeks after they 

 had begun to feed upon the vines. 



The first eggs were seen in the 

 leaves on May 4th, and from this date 

 on the hoppers were laying eggs 

 almost continuously. Egg laying 

 occurs then just about one month after feeding begins on the vine. 

 The eggs are remarkably well tucked away in the leaf tissues by means 

 of a sharp lance-like ovipositor, as shown in figures 5 and 6. 



Fig. 7. Tip of abdomen of male 

 grape leaf-hopper. Much enlarged. 



