196 UNIVERSITY OF CALIFORNIA - EXPERIMENT STATION. 



grape, we confined large numbers of nymphs in all stages on apple, 

 almond, currant, blackberry, and peach, and in each case practically 

 all completed their development in due course. Some of these were left 

 on their food plants long enough to pair and lay eggs, but we were 

 unable to find any evidence of eggs having been deposited. In another 

 place it has been' stated that adult females which were known to be 

 fertilized failed to lay eggs on these same plants. It may be inferred 

 then that nymphs will mature on other food plants, but it is at least 

 unusual, if ever, that eggs wall be laid elsewhere than on the grape. 



THE ADULT. 



Time of Reaching Maturity. The first adults from the spring brood 

 at Lodi w^ere observed on June 8, in 1907, and on June 12, 1908, this 

 being about two months after they had begun to feed on the vine in 

 the spring. By the last of June newly emerged adults were very 

 common. At this time many were seen pairing, indicating that they 

 were fully mature. 



Feeding Habits. The habits of feeding of the adults are not very 

 different from those of the nymphs except that they move about more. 

 They wall be found in greatest numbers on the leaves around 

 the base of the vine and feeding with the nymphs. All 

 through the season the hoppers, in whatever stage they may 

 be, will be most abundant in the interior of the vine. This 

 is probably for protection, since the food supply is not as 

 good as that on the outside of the vine, for the older and 

 less succulent leaves are around the base of the vine. So 

 far as the food is concerned it would appear that the new r 

 Fig 13. The leaves near the tip of the growing shoot would better 



adult grape 



them, as is the case with plant lice and some other 



Copulation and Oviposition. Adults of the spring brood were seen 

 pairing during the last of June, and most commonly about the middle 

 of July. An occasional pair was seen during the first week in August, 

 but after this none were seen throughout the rest of the season. 



Egg laying began with the spring brood during the last week in June 

 in 1907 and the same time in 1908. The overwintering hoppers were 

 also still depositing eggs, so that there appeared an overlapping of 

 the two broods. 



Activity and Migrations. While there was more or less moving 

 about among the hoppers in the same vineyard, no migrations from one 

 vineyard to another were observed until about the middle of July. At 



