BULLETIN 198. THE GRAPE LEAF-HOPPER. 181 



distributed over other food plants. During 1907 the grape leaf-hopper 

 was particularly abundant in many of the vineyards about Fresno, 

 and also in the lower part of the San Joaquin Valley around Lodi. 



LIFE HISTORY AND HABITS. 



OVERWINTERING ADULTS. 



During the colder weather of winter the hoppers may be found in 

 large numbers in the leaves or rubbish in the vineyard, or along the 

 bordering roadsides and fences. Where leaves have been blown together 

 in bunches or lodged in weeds or grass over the vineyard or its borders, 

 hoppers will be especially likely to be present during the colder or 

 wet rainy days of the winter season. They will also be found harbor- 

 ing low down along the fences or in the weeds or other growth among 

 the vines. Alfilaria, one of the commonest plants in many California 

 vineyards in winter, forms a close rosette on the ground, and hoppers 

 will be found abundantly under the low spreading foliage of this 

 plant. 



Food Habits. The grape leaf-hopper feeds on a large variety of 

 plants during the winter season. It will be found feeding chiefly 

 during the warmer days of winter, and resting more or less dormant 

 during the colder or rainy weather. It attacks practically everything 

 that may be growing in the vineyard or vicinity, although a preference 

 is shown for certain plants. Alfilaria is readily attacked by these 

 insects, and where hoppers are numerous the foliage of this plant will 

 be seen to have a pale yellow color as a result of their work. The low 

 spreading foliage seems to offer suitable conditions for the hoppers 

 when they are not feeding, so that they will be found on the underside 

 of these plants almost continuously, regardless of the kind of weather. 

 Burr clover is also readily attacked by the hoppers in winter, as well 

 as rag wee, dock, wild mustard, alfalfa, and several kinds of grains 

 and grasses. They show a preference, however, for such plants as the 

 alfilaria and the clovers as against the grains and grasses. 



The hoppers that were taken into the laboratory in the early spring 

 invariably died in the course of two or three days if deprived of food. 

 Under the same conditions they were easily maintained upon alfilaria 

 or other food. They were confined in lantern globes which were placed 

 in the open window of the laboratory, so that the conditions as regards 

 temperature and moisture were not very different from that of the 

 vineyard. Hoppers were also confined in lantern globes in the vineyard, 

 but in all cases they died very soon without food, though the more 

 dormant they were the longer they were able to survive. 



