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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
problems within his own territory and may even indicate the type of 
agriculture that will meet with fewest entomological obstacles in a 
given region. 
This sounds like a rather ambitious program but is, I believe, one that 
can be substantiated even at this early period of the Survey’s develop¬ 
ment. In the State of Kansas, for instance, entomological records 
have been maintained for more than 50 years, not by any means as 
completely as they are maintained today, but nevertheless completely 
enough to meet the present requirements. Through the kindness of 
Professor G. A. Dean, the Survey was furnished with the chinch bug 
records for this period. These records have been mapped for the 
Survey files, the chinch bug being the first insect to which our new 
system was applied. 
The maps showing the annual outbreaks, indicate that chinch bug 
occurs very generally over the eastern three-quarters of the State of 
Kansas, shifting in destructive abundance from year to year. A state 
map was prepared from the annual maps, upon which a dot was placed 
in each county for each year an outbreak was reported from that county 
during the last 50 years. Here we have very conclusive evidence that 
there is a region in Kansas where the ecological complex is highly 
favorable to chinch-bug development. This region extends over the 
three eastmost tiers of counties, and forms an almost rectangular block 
covering the eastern quarter of the State, wherein the mean normal 
conditions are optimum for the chinch bug. The map shows also that 
over the eastern half of the State average conditions are within the 
critical range of this species and that over the western third the pest 
only occurs when the ecological Conditions are subject to such radical 
departures toward the insect’s optimum as to bring them within this 
critical range. 
One might argue that an insect’s food plants are the limiting factors 
in its distribution. This is-undoubtedly true within certain limits, but 
in this particular case the proposition breaks down. Corn and wheat are 
certainly the two most important food plants of this insect. The chinch 
bug’s optimum range coincides with neither. The most intensive com 
belt is along the northern border of the state extending well beyond the 
optimum range of the chinch bug, while the intensive wheat belt is in 
central Kansas, also well to the west of this chinch bug belt. The area 
of intense chinch bug infestation is not coincident with the two most 
important economic crops it attacks. 
But a glance at the rainfall seems to be much more illuminating. 
