354 



Figure 7 shows temperature-rainfall graphs (xV, B, and C) made 

 up from Weather Bureau records for the years 191-i-l!)17 at Olney. 

 The year 1914-1915, which Mr. Flint rated "moderate" in moths, was 

 most unfavorable in the autumn and, general^, the least favorable of 

 the three years : there was no rain in later winter to compensate for the 

 dry autunm ; the spring was too dry except I\Iay ; and the summer was 

 too wet. In 1915-lG, a year for which Mr. Flint rated moths "moderately 

 abundant," the early autumn was still drier, but later rains compensated. 



90 



'F 



10, 



Fig. 6. (A) Rainfall-temperature diagram for a year in which moths were 

 reported "scarce early" and "abundant late," indicating a fairly favorable fall 

 and winter, an unfavorable spring, and a favorable summer. The typical graph 

 for an "abundant" year (Pig. 4) is also shown here for comparison. 



(B) Mean monthly temperatures for the year Sept. 1, 1916, to Aug. 30, 1917, 

 at Urbana and Carbondale where the "late" larvae were scarce. (They were 

 more numerous at Springfield and Carlinville where July was warmer and 

 drier. This correlation, however, is not clear enough to justify a definite con- 

 clusion.) 



