118 DISEASES OF CROPS. 



the early part of the summer, and place their eggs, it is 

 presumed, upon backward and spring-sown corn, or upon 

 grasses." The larvse of this fly live within the bulb of 

 the wheat stems. 



Prevention. — In districts liable to the attacks of this 

 pest, wheat should not be sown too early. 



Cwre.— Dressing the land with gas-lime, or quicklime, 

 and soot destroys the pupse. 



Ear-Cockles in Wheat {Tylenchus tvitici). In the 

 disease known as " ear-cockle," " pepper-corns," and 

 '' purples," the grains of corn in the spikelets become 

 replaced by galls of blackish hue. The galls are pro- 

 duced by a small nematoid, the Tylenchus tritici of Dr. 

 H. C. Bastian, F.R.S. {Monograph on the Anguillulidce, 

 and Memoirs on the Nematoids : Parasitic and Free). 

 This nematoid belongs to the same genus as those already 

 described under the name of " eelworms." The galls are 

 always to be found within the pales and flowering glumes 

 of infested wheat ; and, according to Dr. Devaine {Re- 

 cherches sur V Anguillule du BU nielU), are " formed 

 from any of the growths belonging to the central part of 

 the flower." Grains affected in the growing crop turn 

 first dark-green, then nearly black. They become mis- 

 shapen, acquire the form and size of peppercorns, and 

 very nearly resemble cockle-seed and wild vetches. The 

 vetch has a smooth skin, whereas the ear-cockle has a 

 rough surface. If seen in the standing corn, they may 

 at once be recognised, as the glumes (chaff) of the diseased 

 grains are spread open to an abnormal degree, while the 

 awns are considerably twisted. If one of the mature 

 diseased grains is cut in two, it will be found to contain 

 a mass of white, cottony-looking substance, which so 

 resembles the meal found in wheat as to be passed by the 



