ENEMIES OF WHEAT 



99 



are the wheat straw worms, army worms, wheat sawflies. In the 

 past, grasshoppers, especially the migratory species, have done 

 enormous damage to wheat, but at present this class of insects 

 usually do their greatest injury to meadows and pastures. 



There are two general causes for the great damage done to 

 wheat and other grain crops by insects. The long hot summers 

 and the present practice of growing somewhat continuously 

 large areas of wheat on the same land produce favorable con- 

 ditions for their rapid multiplication. The rotation of crops 

 and a more thorough and more intensive system of agriculture 

 will tend to hold these insects in check. 



The chinch bug: Adult on the left; eggs upon the right; fou 

 larval stages between. (Adapted from Riley and Webster.) 



151. The Chinch Bug. — The appearance of the six different stages horn the 

 egg to the adult chinch bug is shown in this paragraph. The newly hatched larva is 

 of a pale reddish color 

 with a yellow band 

 across the first two 

 abdominal segments. 

 As the insect changes 

 from one stage to an- 

 other it changes some- 

 what in appearance 

 by becoming increas- 

 ingly darker in color 

 and finally in the 

 adult formby the white 

 wings. So that while 

 in the first larval stage 



the color was principally red and yellow, in the adult form it is black and white. 

 There is also an adult form with short wings. 



The chinch bug passes the winter in the adult form under any object which may 

 offer protection from wet and cold. The grass stools of pastures and meadows, 

 ^^Iks of maize, straw, rubbish in fence and hedgerows furnish them a winter home. 

 Ine eggs for the spring brood are deposited on the plants beneath the soil not 

 far from May ist. These eggs reach the adult stage during July ; while the second 

 brood reaches its maximum damage in August and its adult stage in September and 

 October. It is the first brood that does the most damage to the wheat, r)-e or barley, 

 and less frequently to oats, during the last few weeks of the growth of the crop. 

 In the early part of July this brood migrates to maize fields, thereby injuring this 

 crop also. 



Preventive measures aside from those already mentioned (150) are the clean- 

 ing up or burning of all rubbish or vegetation in fields and fence rows under which 

 the chinch bugs may hibernate. There is no remedy for them while in the wheat 



