PLANT-LICE INJURING THE FOLIAGE 321 



The remedy for those below ground is to draw away the earth from 

 around the base of the tree, in a circle 4 or 5 feet in diameter, and 

 apply 2 to 4 pounds of tobacco dust. The lice on the foliage are best 

 treated with a spray of tobacco extract, or 7 per cent kerosene emulsion. 



Plant Lice on Plum Foliage 



Three species of plant lice are more or less common on the leaves and 

 tender shoots of plums, especially in the spring. They tend to collect 

 in clusters, the leaves are more or less distorted and curled by their 

 attack, and the flowers and fruit may be badly injured. After two or 

 three generations they leave the plum and fly to other hosts. 



The Brown Plum Aphis {Aphis setarice. Thos.) spends the summer 

 on various grasses. It is dark in color and has white-marked legs and 

 antennae. 



The Mealy Plum Aphis {Hyalopterus arundinis Fab.) is covered 

 with a bluish white powder. The back of the body bears three darker 

 obscure stripes, and the shape of the body is rather elongated. The 

 honey tubes are short and rather thick. In summer the lice are found 

 on grasses. 



The Hop Aphis {Phorodon humidi Schr.) flies to hop- vines in 

 early summer, and is a pest rather on the latter than on the plum. 



The treatment is a thorough spraying with tobacco extract or 7 per 

 cent kerosene emulsion just as soon as the lice are first observed. It 

 is important to apply the spray promptly, before the leaves are badly 

 curled. 



The Clover Mite {Bryohia pratensis Garm.) 



This tiny, 8-legged mite swarms over the foliage of clover in some 

 seasons. In the West it feeds also on the leaves of various fruit 

 trees, sucking their juices. The leaves attacked lose their green color 

 and grow yellow and sickly. The mites survive the winter for the 

 most part in the egg stage on the bark of fruit trees. See page 208. 



In smnmer trees should be sprayed with sulphur, 10 pounds to 50 

 gallons of water, adding soap so that the sulphur will not float on top 

 of the water, and keeping the mixture well stirred. Spraying with 



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