﻿36 BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 



curved we teeth, so that when the shield is held beside a vine, the oilcloth will come 

 under the vine to catch the "hoppers" that try to drop to the ground. Cover the oil- 

 cloth with the "stick-em" and all is ready to operate. Two men, each carrying one 

 of these light sticky shields on opposite sides of a trellis of vines, can reach over the 

 shields, jar the vines to disturb the "hoppers" and thus go over an acre of vineyard 

 in a little more than an hour. 



In California, where the vines are not trained to a trellis, Mr. 

 Qua vie found that a screen cage having the inside smeared with crude 

 oil, with one side open and a V-shaped opening cut in the bottom 

 to admit the stem of the vine, could be used quite effectively 

 in the vineyards to catch the adults before egg deposition com- 

 menced. In the course of his field experiments in California Mr. 

 Quayle conducted experiments with suction apparatus for collecting 

 the adults from the vines. He also attempted to destroy them with 

 torches; by the application of dry powders, including lime, helle- 

 bore, and dry sulphur; and also by the fumigation of infested vines, 

 both with cyanid and sulphur gas. None of these latter methods 

 gave results of a practical nature, and the only mechanical method 

 of control against the adults recommended by him is that of the 

 screen cage previously mentioned. 



Destruction of leaves and trash. — Many authors have urged the de- 

 struction of leaves and trash in and adjoining infested vineyards, 

 while the insects are in hibernation, as a means of lessening their 

 numbers. However, since the adults rise in the air and either fly or 

 are carried considerable distances by the winds during the migrations 

 which take place during the spring and fall, there are usually large 

 areas of wood lots and pasture lands at considerable distances from 

 vineyards where swarms of the adults may be found during the 

 winter. Since in many cases these areas of rough land are not con- 

 trolled by the owners of the vineyards there is slight possibility that 

 this cleaning-up process will be undertaken on a large enough scale 

 to be of any great value in lessening the numbers of overwintering 

 adults. Furthermore, at the present time there is a strong tendency 

 toward the growing of some form of cover crop, such as clover, vetch, 

 turnips, rye, oats, etc., in vineyards as a means of furnishing soil 

 protection and fertility; and this is very necessary and desirable in 

 most of the vineyards of the Lake Erie Valley. This would have to 

 be abandoned if the clean-culture method were followed. Observa- 

 tions along this line covering several seasons indicate that where 

 cover crops are growing in badly infested vineyards the number of 

 adult grape lcafhoppers found among the shelter thus afforded is 

 generally very small compared with the number that have migrated 

 to adjacent wood lots and rough pasture lands. In fact, it would 

 appear that there is a tendency for the larger percentage of adults to 

 migrate from the vineyards in the fall, and this migration appears to 

 be their chief mode of dispersal as much as a means for securing suit- 



