748 Grasses and Leguminous Crops in jSTew York 



Pea Aphis 



Another insect which, occasionally does considerable damage is 

 the pea aphis, or plant louse {Aphis pisi Kalt.). It has appeared 

 in pea-growing sections at intervals and practically destroyed the 

 season's crop, but it does not stay with the crop so continuously year 

 after year as does the weevil. The aphis increases rapidly during 

 a period of warm, dry weather ; but a heavy rain, even when the 

 insect is abundant, will sometimes free the vines almost entirely 

 from it. Unless some weather condition acts in this way to destroy 

 the pest, the only hope of the farmer is for the parasites of the 

 aphis to increase sufficiently in numbers to overcome and destroy it. 



