ts 
SPRAYING AGAINST THE GRAPE LEAFHOPPER. a 
foliage only with considerable difficulty. It is in this stage, as men- 
tioned in a previous paragraph, that the insect becomes disseminated 
over vineyard areas. Nevertheless, the spread of the adults does 
not become general until late in the season, when migration for the 
purpose of hibernation takes place. This feature of its movement 
was adequately and strikingly demonstrated in several vineyards 
where experimental work was carried on against the nymphs during 
the season of 1910. In no case was there a serious reinfestation of 
the thoroughly treated vines, although adjoining untreated rows 
were heavily infested throughout the entire season. Hence, we are 
led to the belief that widespread dissemination of this pest takes 
place largely during the fall migration, when the adults rise in the 
air and are carried by the winds, and, again, during the spring mi- 
gration, when they leave their winter shelter and return to the vines. 
Thus the vineyardist who has been successful in destroying the 
nymphs during the summer need have little apprehension of rein- 
festation later in the season from adjacent infested and untreated 
vineyards. 
REMEDIAL MEASURES. 
In discussing the subject of remedial measures for the control of 
an insect pest, it is always highly desirable to take into considera- 
tion cultural and other operations involved in the production of the 
particular crop under treatment in order that the recommendation 
of methods of control which may conflict with the most desirable 
farm practice, or may be impracticable on a commercial scale, may be 
avoided. Modifications in vineyard or orchard management by the 
adoption of new methods may also seriously conflict with earlier 
recommendations which were quite feasible when first stggested. 
Thus, earlier writers have laid considerable stress upon the value of 
clean culture of vineyards and the gathering up of all trash and 
»leaves in and bordering upon them as a means of greatly reducing 
the number of overwintering “ hoppers.” Unfortunately, however, 
this cleaning-up process is impracticable over large areas, and it 
not infrequently happens that adjacent rough lands which furnish 
winter protection outside the vineyards are not under the control 
of the owner of the vineyard. Furthermore, the practice of grow- 
ing winter cover crops of clover, vetch, turnips, etc., in vineyards, 
a practice highly desirable both from the standpoint of increasing 
the fertility of the soil and preventing soil wash during the winter 
months, has become quite general throughout Erie County (see Pl. 
I, figs. 1 and 2). There is no doubt that cover crops tend to hold 
more of the hoppers in the vineyards than where clean culture is 
practiced. Yet many vineyardists are convinced that the ultimate 
advantage to the vine is so much in favor of the cover crop that they 
prefer to continue this practice, if possible, and look for some other 
