THE GRAPE-VINE LEAF-HOPPERS. 35 



"On May 20th a mixture of kerosene and water was ap- 

 plied with a knapsack sprayer having a special arrangement 

 for mixing the two liquids without previously making an 

 emulsion. This liquid w^as used in the proportion of one 

 part of kerosene to fifteen parts of water, and the vines were 

 thoroughly moistened with it. During the spraying the leaf- 

 hoppers rose in swarms and many fell to the ground, but 

 the greater part of these recovered and flew aw^ay to return 

 in the course of half an hour. A few were rendered inactive 

 and appeared paralyzed for a time but very many of these 

 recovered in less than half an hour. The mixture seemed to 

 produce no permanent effect upon the insects, simply be- 

 cause the integument of these minute beings is ver\^ smooth. 

 To remove the offensive fluid the insects used their spiny 

 hind-legs very diligently and with success. 



A solution of tobacco-soap in the proportion of two 

 ounces of the soap to one gallon of water, and another one 

 of one-half pound of whale-oil-soap to the same amount of 

 v^ater v^as applied. Mr. Reel reported on June 10th that 

 neither had been of much use, and that even a few hours 

 after the application but very little difference could be de- 

 tected between plants treated and not treated. 



On July 3rd another trip was made for the purpose of 

 trying a tobacco-extract sold as "Scabcura Sheep-dip." 

 This mixture was applied with a knapsack sprayer in two 

 different strengths; one row of vines was thoroughly 

 sprayed using two ounces of the extract to one pailful of 

 water, and another row was sprayed using four ounces of 

 the extract. The effect was immediate and at the end of 

 two hours but very few of the pests could be seen on the 

 plants. On Aug. 25th Mr. Reel reported as follows: "I am 

 pleased to be able to report that the grape-vines upon which 

 you experimented show a much better foliage than 

 the adjacent rows — although the hoppers appear on them to 

 some extent, the foliage is not so badly browned. I am satis- 

 fied that by spraying in the spring, while the leaves are not 

 too thick, it might drive them away. The stronger solution 

 is by far the most effective one." The action of 

 this extract is almost wholly that of a repellant, and 



