i66 DISEASES OF THE SWEET PEA 



Aphelinus. Another insect which par- 

 asitizes the sweet pea aphids is Aphelinus 

 nigritus^ a parasite also known to attack a 

 number of other green plant lice (fig. 37) . 



FIG. 37. Aphelinus Nigritus; a parasite of the sweet 



PEA Aphis. (after WEBSTER AND PHILIPS.) 



This insect, however, is not so active as 

 the Aphiduis previously mentioned. 



Fungous Pests. The fungi which help 

 to destroy the sweet pea aphids are not 

 as yet well known. Empusa apkidis (fig. 

 30) is the only fungus which has received 

 some attention and study. The others re- 



