76 



several oil and water pumps we used could be depended upon to 

 throw the scheduled amount of oil. The suj)posed 5 per cent oil 

 spray varied so much that too much injury resulted to the foliage 

 and we had to abandon these pumps. AVe believe it is practicable 

 to use two puraps, one for whale-oil soap (1 pound in 5 gallons of 

 water) to knock the '"hoppers" down, and the second an oil and 

 water pump with a longer hose to follow close behind and hit them 

 on the ground with a 25 per cent oil spray. TTater will not bring- 

 down satisfactorily. It is of the utmost importance to kill all of the 

 hibernated adult "hoppers" possible in the spring, for they often do 

 as much injury as their children later in the season. We believe 

 that if d^ to 75 per cent of them could be killed then that the vine- 

 yards would not suffer seriously during the rest of the season. 



The young "hoppers" or nymphs are quickly killed when hit with 

 a weak soap or oil spray. We sprayed many acres with whale-oil 

 soap (1 pound in 10 gallons of water) early in July, with very success- 

 ful results. The keynote to success is in hitting the little nymphs on 

 the undersides of the leaves. To do this it is necessary to stop at 

 each vine and with underspray nozzles direct a forceful and fine spray 

 onto the undersides of the leaves. Vineyards can be thoroughly and 

 effectively treated in this way in July for about 85 per acre, and one 

 treatment is usually sufficient to reduce the pest far below the danger 

 limit. Our sprayed vineyards remained green until frosts came, and 

 the fruit and wood thus fully ripened. The fruit sold above the mar- 

 ket price, as it was riper and sweeter. 



As no one had worked out the life history of this common pest, we 

 made careful studies in the field and insectary. which resulted in 

 many new and interesting facts. Recent writers have guessed. there 

 were three or more broods of the "''hoppers" in a year. Our observa- 

 tions, extending over two years, lead us to the following conclusions 

 regarding the life and habits of the grape leaf-hopper in Xew York. 

 The adults hibernate largely in nearby grass and woodlands, and 

 emerge about May 1 to feed for two weeks or so on various plants, as 

 strawberries, dewberries, and raspberries, their reddish, winter color- 

 ing changing to a lemon yellow ; then they go to the grape foliage, 

 and the insect spends the rest of the season thereon. About June 1 

 egg laying begins and continues for several weeks, the eggs being 

 stuck just beneath the lower skin of the leaves, usually oue in a place, 

 but sometimes six or more in a row. They hatcli in about two weeks. 

 The young * ; hoppers" live on the undersides of the leaves through 

 five different nymph stages, their cast skins often remaining on the 

 leaves for weeks. The nymphs run rapidly, but, contrary to tradi- 

 tion, they do not hop or leap. After about five weeks of this nymphal 

 life they appear as flying and leaping adults in August. Evidently 

 some of the first of these adults to appear lay eggs which develop a 

 partial second brood of nymphs in Xew York, but most of them soon 





