April, ’23] 
hyslop: insect pest survey 
219 
Here we see that the westmost limit of the area in the state having a 
minimum mean annual rainfall of 30 inches runs west of the optimum 
chinch bug belt and that two lines of 34 inches minimum mean annual 
rainfall lie mostly within this belt. An imaginary line probably limiting 
the 32-inch minimum mean annual rainfall area in Kansas would practi¬ 
cally coincide with the westmost border of the optimum chinch bug area. 
Data of this type, when brought together for all the states, will 
possibly show a maximum rainfall limit. It may not be an annual 
mean but a monthly maximum or even a daily maximum within a very 
limited period. 
Cases may develop in which an entirely different factor or group of 
factors may be critical, such as elevation, rate of evaporation, intensity 
of light, soil, vegetation, or natural enemies. Can anyone doubt that 
the determination of the critical ecological factors will make possible 
the prediction of insect outbreaks? Is it not evident, if an insect is 
confined to a given region in which a given set of known conditions 
prevail, and if this insect only occurs outside of this region when the 
conditions in the contiguous territory are modified, either by departures 
from normal climatic conditions or by the handicraft of man, that we 
can, by examining the known conditions with the current conditions, 
foretell insect outbreaks as accurately as weather conditions are now 
prognosticated ? 
Another phase of the value of Survey work is the forecasting of the 
probable spread of newly introduced pests. This, of course, is subject 
to much more frequent error than the direct record type of forecasting 
just outlined. In this work we take the normal range of a closely allied 
species and use this as an index of the possible extent of its newly intro¬ 
duced congener. For example, the Mexican bean beetle within the last 
few years has become a serious pest in the Lower Mississippi Valley 
region. This pest was normally confined to the foothill regions of the 
Southwest and Mexico. It is now well established over Alabama, 
parts of Georgia, North Carolina, South Carolina, Tennessee, and 
Kentucky. How far to the North, South, and East will this insect be 
able to maintain itself? We turn to the closely related species, Epi- 
lachna borealis as an indicator and find that this species has been recorded 
over practically the entire humid austral region of Merriam. The two 
beetles hibernate under very similar conditions. The normal food of the 
introduced species is abundant throughout this entire region, so we have 
evidence which should lead the thinking entomologist to organize for 
the advent of this species as far north as Southeastern Massachusetts 
