80 



DISEASES OF CROPS. 



in the leaves and stems of grasses. The pupse of this 

 insect are of an ochre colour. Chlorops has several foes 

 belonging to the Insecta ; the most important of which 

 are Pteromalus micans and Caelinius niger — two flies 

 which lay eggs within the bodies of the maggots of 

 Chlorops tceniopus. The larvse produced from these eggs 

 feed and live upon the maggots of Chlorops, reducing 

 them to mere empty skins. 



It has been estimated that this fly caused a loss of from 

 3 to 14 bushels of corn per acre (Whitehead's "Reports"). 



Fig. 33. — The Corn Saw-Fly {Gephus pygmcsus). 



A. The fly (uat. size). 



B. Larva (nat. size). 



0. Infested stem (enlargecl). 



Prevention. — (1) Grasses, etc., infested with Chlorops 

 should be eaten by sheep. (2) After thrashing infested 

 barley or wheat, the chaff, etc., should be burnt. (3) 

 Pulling up all stunted and infested plants has a tendency 

 to greatly reduce the attacks of this pest. (4) Promote 

 healthy and vigorous growth by the judicious use of 

 soluble manures ; for barley is a " shallow feeder " (i.e., 

 it obtains nourishment from the surface soil), and requires 

 easily assimilable plant-foods. 



The Corn Saw-Fly {Cephus pygmceus, Pig. 33) 

 belongs to the Hymenoptera, and attacks barley and other 



