76 



several oil and water pumps we iisod could bo depended upon to 

 throw the scheduled amount of oil. The supposed 5 per cent oil 

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

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

 to use two pumps, 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. Water will not bring 

 down satisfactorily. It is of the utmost imiwrtance 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 

 tliat if oO to 75 jDer cent of them could be killed then that the vine- 

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



The young "lioppers" or nymphs are quickly killed when liit with 

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

 soap (1 pound in 10 gallons of water) eai-ly in Jul}', with very success- 

 ful results. The keynote to success is in hitting tlie little nj^mjihs on 

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

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

 onto the undersides of the leaves. Yinej-ards can be thoroughly and 

 effectively treated in this way in July for about $5 per acre, and one 

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

 limit. Our spraj^ed vineyards remained green until frosts came, and 

 the fruit and wood tlius fully ripened. The fruit sold above the nuir- 

 ket price, as it was rii3er and sweeter. 



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

 made careful studies in the field and inseetary, Avhich 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 grap(^ leaf-hopper in New ^'ork. 

 The adults hibernate largely in nearby gi-ass 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 tliereon. About June 1 

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

 stuck just beneath the lower skin of the leaves, usuallj^ one in a place, 

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

 The j^oung "hoppers" live on the undersides of the leaves through 

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

 leaves for weeks. The njnnphs run rapidly, but, contrary to ti-adi- 

 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 New York, but most of them soon 



