355 



May was nearly normal in total precipitation for an abundant year, but 

 the summer distribution of rain was unfavorable to moths. The autumn 

 and winter were too dry in 1916-lT. in which Mr. Flint rated the moths 

 "moderate." Of these three years, graph C conforms most nearly to that 

 of a scarce year. 



c. Number of late larvae. 



The damage to the apple crop of 1914 was, to a considerable extent, 

 due to a large nmnber of late larvae. As nearly as can be judged, such 

 abundance of late larvae is one of the characteristics of the autumn 

 of an "abundant" year. The conditions favoring the development of 

 a third generation are shown in Figs. 4 and 5. The season 1916-17 (Sep- 

 tember 1-August 31) was especially significant in this respect, as there 



Fig. 7. Ball-Taylor diagrams, or hythergrapbs, for three years at Olney. 



were few or no late larvae at Urbana and Carbondale, while at Springfield 

 and Carlinville there was a small late or third generation of larvae. The 

 rainfall-temperature diagrams (Fig. 6B) for the two localities without 

 late larvae show dr\' autumn and wet spring characteristic of "scarce" 

 years. The ditYerence from the "abundant" years is striking. The absence 

 of late larvae in this one year was associated with a rainy July at Carbon- 

 dale and with low temperatures at Urbana. 



