EXPERIMENT STATION BULLETINS. 



205 



land, it is well to arrange the rotation so as to avoid, as far as possible, 

 bringing corn and grass together, in land subject to their invasions. 

 They are especially apt to be killed off by diseases and natural enemies, 

 so that they come and go with no apparent reason for so doing. They 

 seldom remain very numerous in one field for more than one or two 

 vears, because of these enemies and diseases. 



INSECTS AFFECTING THE STALK. 



Corn-stalk Borer {Helotrypa atra). 



In his report for 1888, Professor A. J. Cook records a corn-stalk 

 borer from northern Michigan. He describes the injury as quite serious 

 due to a longitudinal tunneling of the growing stalks. The larvae of 

 this insect are said to be much like the ordinary arnij'-worms, and the 

 adults closely resemble the moths of the common cut-worms. The writer 

 has not, as yet, seen this pest. 



Barred-winged Onion-maggot {Chaetopsis aenea) . 



This insect is discussed among the onion insects. It has not, thus 

 far, been found in corn in Michigan, but is recorded as having worked 

 in corn-stalks in Maryland. As it is common in our State, its name 

 should be included as a possible sweet-corn pest. 



Bill-bug {Sphenophorus sculptilis). 



Fig. 55. — Corn Bill-bug, enlarged. Original. 



A few hundred miles to the south of us, the corn bill-bugs are not 

 so uncommon as in our State. The season of 1904, however, witnessed 

 the demolition of several large corn fields by this destructive pest. The 



