6 



develops when most plants attacked by chinch bugs, excepting 

 corn, are either dead or have ceased to grow rapidly, and the 

 alternative food resources of the insects must be relatively few and 

 slight. 



SUCCESSIVE ABANDONMENT OE CORN AND WHEAT. 



Q The ideal procedure with wheat and corn, is doubtless the sup- 

 pression of corn one year and of wheat the next, catting down the 

 second chinch-bug generation of one season and the first of the 

 following. The effect of this rotation also was indicated by a 

 spontaneous experiment made by nature in parts of Marion and 

 Clinton counties in 1887 and 1888. Here the severe drouth of 

 1887 cut short the corn, in some neighborhoods early destroying 

 it, so that not a stalk in acres ever formed an ear; and the wheat 

 sown the following autumn was so badly winter-killed that prac- 

 tically all was plowed up in spring, the ground being replanted 

 to other crops. As if in consequence of these occurrences, the 

 chinch bugs in this region in the spring of 1888 were much fewer 

 than in 1887, not more than one fourth as numerous according to 

 my own judgment, local observers putting the difference at about 

 one half. 



SECONDARY EFFECTS OF THE ABANDONMENT OF WHEAT. 



Suspension or abandonment of wheat culture has been for a 

 hundred years the favorite method of evading the ravages of the 

 chinch bug; but, so far as I know, this measure has heretofore 

 been taken only when the insect hordes were about to disappear 

 under the action of other and more general causes, and the real 

 •effect of this variation in farm management has consequently not 

 been clearly demonstrated. Other unplanned experiments of the 

 kind which I have found so instructive lately, have thrown much 

 light on this subject also. 



About Edge wood, in Effingham county, where scarcely any wheat 

 was raised in 1887, it was clear to a demonstration, June 21, that 

 the chinch bugs had lived and bred since early spring in timothy 

 meadows, many of which were already hopelessly ruined for the 

 year; and from these meadows the bugs were then making their 

 way to oats and corn. Oats fields had also become infested by 

 flying adults in spring, and young and old were everywhere dis- 

 tributed, many acres of oats being dead and dried up. 



In some parts of Clay county — notably about Flora — the amount 

 of land in wheat had been gradually diminished from year to 

 year, until, in the spring of 18S8, I could find but two small 

 fields in a consi(lora})lo district. The insect wave had here, how- 

 ever, but just reached its height, and to the general alarm, not 

 only were the bugs more numerous than ever before, but they 

 were widely and generally dispersed through oats and young 



