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138 THE SPRING GRAIN-APHIS OR GREEN BUG. 



Mr. C. N. Ainslie, began experiments with a barrel pump,, loaned by a 

 market gardener. One plat was sprayed with 5 per cent kerosene 

 emulsion; another with 10 per cent kerosene emulsion; a third plat 

 with ordinary hard soap, 1 pound to 4 gallons of water; a fourth plat 

 with whale-oil soap, 1 pound to 6 gallons of water. The spraying 

 was done carefully, so as to reach every aphis possible. Upon 

 examination the next day it was found that the 10 per cent emulsion 

 and the hard soap had injured the plants. Not more than 50 per 

 cent of the plant-lice were killed in any of the experiments. On the 

 15th of April the sprayings were repeated with similar results. All 

 of the aphidids could not be reached, no matter how thoroughly 

 the spraying was done. It was quite evident that unless the ground 

 was almost soaked there would be little or no relief. These spray- 

 ings cost at the rate of about $4 per acre. 



During the latter part of July it was found that Toxoptera was 

 very abundant on the lawns of the Department of Agriculture at 

 Washington, D. C. This outbreak became known to Mr. E. M. 

 Byrnes, Superintendent of Experimental Gardens and Grounds, 

 who at once had the entire infested block sprayed with a solution of 

 one-half gill of blackleaf tobacco extract to each gallon of weak 

 soapsuds. The application was, however, ineffective. Four days 

 later a strip through this plat was thoroughly saturated with a 

 strong solution of barnyard manure, made by soaking the manure 

 in water. While there was no evidence that this killed any of the 

 " green bugs," after nine days the pest was visibly less on this area 

 than where the application of manure solution was not made. 



A series of experiments was then undertaken under the senior 

 author's direction by Mr. E. O. G. Kelly, as follows: 



Tobacco dust was applied at rates of one-fourth, one-half, and 

 1 pound to each 100 square feet, but after over a week had elapsed 

 from the date of application no effect was to be observed and no dead 

 insects were found. 



Kerosene emulsion was applied at 8 and 10 per cent strengths, 

 and at the end of nine days no " green bugs" were to be found on the 

 areas so treated. Also there was no perceivable injury to the grass. 



Whale-oil soap solutions, varying in strength from one-fourth of 

 a pound to 2 pounds of soap to each 5 gallons of water, were applied 

 to similar areas. In this case the stronger solution injured the 

 grass slightly, but not permanently; in the case of the lesser strengths 

 there was no injury to the grass whatever. The effect on the " green 

 bug" was the same in every case. They were not only literally 

 exterminated over the areas treated, but the applications seemed to 

 protect from a reinfestation, in case of even the weakest solution. An 

 examination five days after the application was made revealed the 

 " green bugs" in myriads and breeding freely on the untreated space, 

 while only 8 inches away and on the treated area living bugs were 



