588 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
Fig. 16.—Comparison of the number of migrating larvae recovered 
daily in the spring of 1923 with the mean night temperatures. The scale 
to the left indicates number of larvae which is shown by the blocked-in 
area. The scale to the right applies to the mean night temperatures 
shown by the broken line AA. Progress of pupation is shown by the 
dotted line BB. Blank spaces in the records of number of larvae means 
that traps were not examined on those days, the record for the day 
immediately following showing the migration of two nights. 
