57 



frequency, as a coiiseciueuce, with wliicli the insects may l)e fouiul in 

 various stages at the same time have sometimes led to the inference that 

 there were several generations in a year. Injury to corn, however, is in 

 all cases limited to spring and early summer, cc^asing altogether by the 

 middle of July even in the most serious cases. Corn not killed or crip- 

 pled by these insects while it is young soon grows beyond their reach, 

 and they then leave the field in search of more practicable food. 



The eggs of the Illinois species studied, are laid mainly in May and 

 June in the roots or stems of the plants; larvae may occur throughout 

 June, July, and August; and the beetles emerge in late summer and in fall. 



Measures of Prevention and Remedy. — Probably no steps could be 

 taken to arrest the injury to corn in spring by these beetles, and the 

 only resource at that time must be replanting of the injured hills. To 

 avoid repeated destruction, this should be postponed as late as prac- 

 ticable, but it would be virtually safe after the middle of June. The 

 swamp bill-bugs are likely to continue their destructive work through 

 June and well into July, and with them, consequently, this measure 

 would usually fail, and the only alternative i-emaining is the [)lanting of 

 the ground to some crop not liable to injury by these beetles. It appears, 

 from observations made in 1902, that injury by the swamp species may 

 be forestalled by breaking up the sod in early fall, and it has also been 

 repeatedly observed that corn growing upon timothy sod of early fall 

 plowing was relatively — usually, indeed, completely — free from bill-bug 

 injury the following spring. 



For details concerning the several s[)ecies the reader is referred to 

 an article on the corn bill-bugs published in my Fifth Report, the six- 

 teenth of this office (1890), and to another on "The Corn Bill-bugs in 

 Illinois, " in my Eleventh Report — the twenty-second of the office (1903). 



THE CHINCH-BUG. 



Blissus leucopterus Say. 

 (Plate T.) 



This notorious insect, one of the very worst enemies of Airuu-icaii 

 agriculture, is, on the whole, the most destructive to corn of all the 

 insect species to whose attack that crop is subject. It is true that in 

 some parts of the state it has now been virtually unknown for many 

 years, and that where it is most commonly destructive, periods of several 

 years may succeed each other with no noticeable loss to the corn farmer 

 on its account. There are considerable districts, however, in which 

 it is permanently present in numbers sufficient to do every year more 

 or less injury in corn fields, varying from what may be described as 

 trifling to the total destruction of the entire crop over many square miles 

 of territory. It is estimated that the total agricultural losses due to the 



