III. EXPERIMENTS IN THE CONTROL OF THE 

 ROOT FORM OF THE WOOLLY APPLE APHIS. 1 



By B. R. Leach, Scientific Assistant, Deciduous- Fruit Insect Investigations. 



CONTENTS. 



Introduction 29 



Use of carbon disulphid in water 29 



Early records 29 



Experimental work with this method 30 



Advantages of this method 35 



Disadvantages of this method 35 



Use of sodium cyanid in solution 35 



Experiments on vines in French vine- 

 yards ■-.. 35 



Use of sodium cyanid — Continued. 



Experiments at Winchester, Va 



Advantages and disadvantages of the 



method 



Use of kerosene emulsion 



Preliminary experiments 



Field experiments 



Deep planting 



Summary 



Page. 



36 



37 

 37 

 37 

 33 

 38 



INTRODUCTION. 



During the seasons of 1914 and 1915 a series of experiments on the 

 control of the root form of the woolly apple aphis (Erisoma lanigerum 

 Hausmann) was conducted in Virginia, the work being based on the 

 results obtained by French investigators in the employment of carbon 

 disulphid and sodium cyanid in solution against the grape phylloxera. 

 The opportunity also was afforded of obtaining data on the use of 

 kerosene emulsion and on the effect of deep planting as preventives of 

 woolly apple aphis injury. 



Little work appears to have been done by American entomolo- 

 gists in the employment of carbon disulphid and sodium cyanid in 

 solution as a control for soil-inhabiting insects. The data obtained 

 as a result of the experiments herein reported are presented in the 

 hope that other experimenters will have opportunity to carry out 

 further tests along these lines. Much additional information con- 

 cerning these treatments is desirable, especially that which may be 

 acquired through experiments carried on under a variety of climatic, 

 crop, and soil conditions. 



THE USE OF CARBON DISULPHID IN WATER. 



EARLY RECORDS. 



The use of carbon disulphid in water was first proposed by Cauvy, 2 

 of France, in 1875. 



It was found that a solution containing from 0.5 to 1.2 per cent 

 of carbon disulphid will kill the grape phylloxera in 24 hours. The 



1 Eriosoma lanigerum Hausmann; order Hemiptera, suborder Homoptera, family Aphididae. 



2 Bourcart, E. Insecticides, Fungicides and Weedkillers, p. 74. London, 1913. 



29 



