10 BULLETIN 345, U. S. DEPARTMENT OF AGRICULTURE. 
Itis not necessary to point out that there were several other variables 
among the conditions of these experiments. For example, humidity 
is no doubt an important factor, but the lack of complete and accu- 
rate records of the relative humidity prevents making any statistical 
analysis of its influence on the length of the preoviposition period. 
UTAH 
IGT 
TETRA 
UGTA 
ALT 
LTTE 
ULI SMUATITE 
AAS 
ST 
i0 11 12 13 14 15 16 17 18 19 202 
rool 
95 
90 
fo.) 
uo 
fo.) 
ce) 
( Original.) 
oO 
of the house fly. 
fo) 
on 
Average mean lemperature in degrees ce 
(oa) “J 
[o) © 
oe 1.—Curve showing correlation between the average mean temperature and the length of the preoviposition period 
$5 
pay shel aee Period ir days 
It is interesting to note that Bishopp, Dove, and Parman (1915), in 
experiments at Dallas, Tex., obtained a 4-day record at an average 
mean temperature of 87.5° F., while the 4-day records at Arlington, 
Va., averaged 79.5° F. This and other differences between their 
results and those recorded in the present paper may in large part be 
due to the differences in the relative humidity of the two localities. 
