BULLETIN 198. 



THE GRAPE LEAF-HOPPER. 



197 



this time, and later, hoppers were seen in some cases flying about the 

 farmhouses some little distance from any vines. They were seen at 

 night, and when the weather was warm and calm. They appeared not 

 to be going in any particular direction. Such migrations or activity 

 were only very occasional, and so far as we could see the numbers in 

 the vineyards were not changed. In the cases noted there was no 

 particular reason for the migration on account of food. We believe 

 that favorable weather conditions caused greater activity on the part 

 of the insects, and that they are just as likely to go back into the 

 same vineyard as to make a distinct migration in a definite direction 

 for change of food or other reasons. 



Activity of the Sexes. Both males and females seemed to be equally 

 active as seen from the proportion of the sexes taken in the air 

 with a net when disturbed, and the fact that they were found in all 

 situations in about equal numbers would seem to indicate that there 

 is no difference as regards the activity of the sexes. 



Proportion of the Sexes. 



Differences in Coloring Due to Age. The hoppers in winter are 

 distinctly redder in color, i. e., the markings are more pronounced than 

 at any other season. The reddish color becomes more conspicuous as 

 the winter season approaches, after they have left the vine and began 

 to feed upon their winter food plants. In the spring after they have 

 been feeding for a few weeks on the vine they become distinctly paler 

 in color again. This less conspicuous marking is then maintained 

 throughout the life of the insect surviving the winter. While they 

 have become distinctly paler in color after feeding for two or three 

 weeks on the vine in the spring, they are not so pale colored as the 

 newly hatched hoppers, and the individuals of the two broods may 

 be distinguished for a time after their emergence. The hoppers of the 

 second brood that. are on the vines in the fall take on the more con- 

 spicuous coloring with the approach of the winter season, and this 

 more pronounced marking remains until after they have fed for a 

 few weeks on the vine in the following spring. 



