120 CULTURE OF FARM CROPS. 



stractive of garden and farm produce. We illustrate in 

 tig. 1 7 a wing of an insect of this order. The larvse of the 

 coleopterous insects or beetles are popularly described or 

 known as grubs the larvse of the lepidopterous insects, or 

 butterflies, moths, &c., as caterpillars and those of the 

 dipterous insects, maggots. Having thus explained very 

 briefly the chief characteristics of insect life, we now pro- 

 ceed to describe the various insect parts of the wheat crop, 

 beginning with, 



15. "Ear-cockle" "pepper corn," or "purples" by all of 

 which names this is known. The grains of wheat infected 

 with this disease become of a dark green colour, which 

 ultimately changes to one nearly black; they lose their 

 usual oblong rounded shape, and become nearly spherical 

 like a small peppercorn hence one of the names of the dis- 

 ease ; the husks or chaff spread open ; the awns are twisted ; 

 so that infected ears are easily observable. On crushing the 

 grains thus diseased they are found to contain no flour but a 

 moist cottony substance, which, under the microscope, and 

 when moistened with water, is discovered to be a moving 

 mass of exceedingly minute eel-shaped animalculae, and to 

 which the name is given of vibrio tritici. The disease 

 occasioned by the attacks of this animalcule is stated to be 

 very injurious to the grain; but it is by no means com- 

 monly met with, or perhaps, to state the matter more cor- 

 rectly, it is not commonly suspected. On grinding the cot- 

 tony mass of animalculae it is said they remain behind with 

 the bran and not to pass through with the flour. " When a 

 small grain of wheat is seen by the side of one infected 

 with the vibrio, the young plant which springs from the 

 former is not infected before March ; but then the animal- 

 cules begin to find their way from the blighted grain into 

 the earth, and thence into the young corn. They gra- 

 dually ascend within the stem till they reach the ovule (or 

 young state of the seed) in the flower-bud even before the 

 ear has shown itself." A remarkable peculiarity connected 

 with this animalcule is its vitality, which they will retain 

 for six or seven years. Even if kept till they are reduced 



