o4 
paring the dates upon which the maximum emergence was known to 
have taken place at different points in different years with a curve 
of the mean monthly temperature for that year and the normal mean 
monthly temperature for a series of years, it was found that such 
was not the case. In some years the time of maximum emergence 
was before the normal date at which the mean daily temperature 
became 78°, and in others later, depending upon the departure from 
normal of that individual season. But the date of maximum emer- 
gence did not depart from the normal theoretical date upon which 
the mean daily temperature becomes 78° to the same extent as the 
departure from normal was indicated by the mean monthly tem- 
perature curve for that year. The temperature may have reached 
78° on June 1, for instance, where nominally it would have reached 
that point May 1, and still in that year the weevils emerged in maxi- 
mum numbers but a few days after the normal time. Sufficient 
accurate data are not at present available to make a positive statement 
as to what governs this date of maximum emergence, but. from all 
data available and from a careful study of the temperature curves, 
I wish to offer the following hypothesis, which I believe will be found 
to come very close to determining this date and possibly that of other 
insects hibernating as adults.* 
The date of maximum emergence from hibernation, or the date of 
oviposition, will depart from the normal date—which for the boll 
weevil may be considered the date when the temperature reaches 78° 
F. or thereabouts—by the amount of the accumulated difference in 
temperature between the normal daily mean and the daily mean for 
that vear; or we might term it the accumulated departure from nor- 
mal for that year during the period commencing one month prior to 
the point of departure of the vearly line from the normal after the 
point of first emergence and the date upon which the total accumulated 
temperature for that year will equal the amount of accumulated 
temperature in the normal year between the first date of this period 
and the date of maximum emergence.” 
«The writer proposes to make studies of other insects to determine whether 
any general laws may be defined upon this point, and will be glad of any coop- 
eration possible from others, as observations at several points distant from one 
another are necessary to make such work of value. 
bIt seems desirable to insert a figure illustrating the hypothesis proposed, 
as was done with drawings before the Association. For this the normal 
monthly mean temperature curve for Victoria, Tex., and the monthly mean 
temperature curve for the same place for 1904 have been selected. The figures 
are those of the United States Weather Bureau. In platting the curves we 
have used the 15th of the months for which the mean temperature is given. 
The “mean monthly temperature” as reported is the average for the whole 
month. It is evident that in most cases the 15th of the month would more 
correctly approximate tbis temperature than the 380th, upon which date it is 
