60 



nozzle throwing a strong stream b}^ pumping the liquid back upon 

 itself. When properly combined the mixture will have become of the 

 consistenc}^ of thick cream. It is then placed in moderately tight 

 receptacles, and will keep almost indefinitely until required for spraj"- 

 ing, when it is to be diluted. For plant-lice this staple emulsion is 

 usually diluted with from 10 to 15 or 20 parts of water. 



Its habit of feeding on the lower surfaces of leaves renders the 

 melon louse more difficult to reach b}^ means of a spra}' than insects 

 which live on the upper surfaces. In the application of an emulsion 

 or other wash, therefore, it is necessary that the hose be fitted with an 

 upturned nozzle in order to secure the under spra3dng of the leaves, 

 which is the principal resort of plant- lice and many other sucking 

 insects. 



It is of the utmost importance that the spra3^s or other remedies 

 be applied on the first appearance of the insect in order to check it 

 before it succeeds in obtaining a good start and to prevent its further 

 development. 



Spraying with water. — A strong stream of water from a hose 

 directed on plants, so as to hit the insects, is of much value in dislodg- 

 ing them from the plants, to which they do not usually succeed in 

 returning, and where this can be readilj'^ done more elaborate reme- 

 dies are unnecessary. 



Pyrethrum administered with a powder bellows to the lower sides of 

 leaves is also valuable and particularly effective on young plants. It 

 is, however, expensive, and can not be profitably used in large fields. 



Clean culture and fall plowing should be followed as the most effect- 

 ive measure of prevention of attack by plant-lice as well as other 

 insects, and this includes the keeping down of weeds after the main 

 crop has been gathered until the next crop is planted, this treatment 

 serving to rid the fields of many pests, particularly those which do 

 not fly readih', b}" depriving them of food. 



Fumigation methods. — In \Qvy recent years two methods of fumiga- 

 tion have been rather extensively practiced as a means of destroying 

 the melon louse and related insects on valuable plants. It is doubtful, 

 however, if either of these remedies would be necessarj^ on beets 

 except in regions where injury is more extensive than has thus far 

 been reported. 



If careful watch is kept for the first appearance of this plant louse 

 it can be more thoroughly eradicated by means of fumigation than by 

 any other method. The method of application of bisulphid of carbon 

 consists in covering the affected plants on the first appearance of the 

 pest with a tub or similar receptacle, and evaporating the chemical 

 beneath this at the rate of a dram to 1 cubic foot or less of space 



