EXPERIMENT STATION BULLETINS. 321 



and die. Here on the twigs the females settle for winter in a partially £?rown 

 condition. In the spring, they rapidly complete their growth, lay batches of eggs 

 and dry up. The Insect works on a number of other plants and trees, loving 

 especially the soft maple. 



KEMEDIES. 



When only a few are present, they may be scraped off the vines with a knife, 

 but when they occur in large numbers it is necessary to use a spray. Apply 

 kerosene-emulsion just after the young hatch in June and July, diluting the 

 emulsion about eight times, or else spray in the winter time with one of the 

 contact insecticides recommended for the San Jose scale. 



Apricot-scale (see Insects affecting the plum). 

 Tree Cricket (see Insects affecting the blackberry). 



AFFECTING THE FOLIAGE. 



The Grape Leaf-hopper. (Erythroneura vitis.) 



One of the most destructive grape insects in this part of the country, is the 

 leaf hopper, sometimes erroneously called the thrip. Almost minute in its dimen- 

 sions, measuring scarcely more than an eighth of an inch in length, inconspicuous, 

 jumping and flying away on the slightest disturbance, it hardly seems possible 

 for so small a creature to work such havoc. It occurs in great numbers, literally 

 in great swarms. The prevailing colors are yellowish-white and bright red. The 

 insect is. many brooded, the eggs being placed in cavities cut in the leaf. The work 



Fig. 43. — Grape Leaf hopper, from Saunder's Insects Injurious to Fruits. 



of the leaf hopper shows in browned and curled leaves, and consequent poor fruit. 

 The writer has seen whole regions of vineyards where the foliage appeared as if 

 scorched, just such -a result as might be brought about by continued hot winds. 

 The damage in such cases is very severe. 



REMEDIES. 



The insect passes the winter in rubbish, under leaves, and in all sorts of 

 neglected situations. The removal of such rubbish late in the fall, after the 

 insects have taken up winter quarters, will work wonders. Sometimes it is 

 possible to burn over grass and rubbish on the edges of vineyards, destroying im- 

 mense numbers and lessening the next year's supply. 



The writer has obtained some results by spraying with strong tobacco-extracts, 

 which act as repellants, but such sprays are expensive and give only partial im- 

 munity. The most promising remedy is one devised by Professor Slingerland 

 of Cornell. He found that by applying a weak spray of kerosene and water 

 emulsified by a mechanical mixer (a knapsack pump which takes the oil from 

 one tank and the water from another and mixes them in any proportion), he could 

 easily knock the insects off the vines on to the ground, and then by changing the 

 proportion of oil in the spray to strong emulsion, he could spray the insects on 

 the ground and kill them. The difficulty lies in the fact that the insects will stand 

 a good strong emulsion such as is ordinarily used, and in order to kill them 

 direct, it becomes necessary to use a spray stronger than the vines will stand. 

 In th^s double spray, which is cheap, we have an effective remedy. 

 41 



