Il6 INSECTS INJURIOUS TO VEGETABLES 



the "lice," which in a very few weeks destroy a crop. Attack 

 is seldom noticed until May in the more Southern States in 

 which the insect is found, and a little later in its more northern 

 range. It hibernates on clover and vetch, and from these plants 

 spreads by flight in April and May to peas. The females at 

 certain periods produce living young. These attain maturity in 

 from ten to fifteen days, and possibly in less time in the hottest 

 weather. Several generations develop each year. As instance 

 of the reproductive powers of this insect. Prof. W. G. Johnson's 

 estimate is interesting. Females produce from no to 120 young. 

 Calculating from the average number of insects produced each 

 day (six), one individual would in one year become the pro- 

 genitor of 423,912 "lice." 



In some instances natural enemies of the pea aphis have done 

 efficient service. Seldom, however, do they destroy the insects 

 sufficiently early in the season to save a crop. 



Kerosene-soap emulsion, carefully prepared and diluted with 

 about twelve parts of water, and sprayed upon the plants upon 

 the first appearance of the "lice," so that the leaves are wet on 

 both the under and upper surfaces, has been found to be the 

 most effective of the insecticides tried. A stronger solution is 

 apt to scald the plant, particularly while the vines are young 

 and tender. The cost of the emulsion, however, and the diffi- 

 culty of under-spraying, its rapid evaporation, and the necessity 

 of frequent applications, is such as to hardly warrant its use. 



Brush and cultivator method. — The peas are grown in rows 

 sufficiently wide apart as to admit of a one-horse cultivator be- 

 tween them. The "lice" are brushed from the plants with 

 boughs of pine with their leaves on, and a cultivator follows 

 down the rows immediately afterward. This method should be 

 practiced in the heat of the day, when the ground is dry and 

 hot, and a repetition o^ the brushing is necessary every three 



