10 
BULLETIN 640, U. S. DEPARTMENT OE AGRICULTURE. 
favorable to fruit-fly increase. At Honolulu the temperature rarely 
drops as low as 58° F., and then only for a few hours during one or 
two nights in the year. 
The daily range in 
temperature is small, 
averaging between 8 
and 11 degrees, while 
the normal monthly 
mean temperatures 
range between 70.9° F. 
in the winter and 79° 
F. in the summer. 
Biological work has 
shown that even the 
lowest monthly means 
of localities up to 1,500 
feet elevation have lit- 
tle effect upon the fruit 
fly other than to retard 
somewhat its develop- 
ment. It is never cold 
enough throughout the 
coastal regions of Ha- 
waii to render either 
the adults or the larvae 
inactive . There are 
no periods of the year 
at any Hawaiian port 
when climatic condi- 
tions are unfavorable 
for fruit-fly increase. 
A continuous temper- 
ature of 58° to 62° F., 
or the lowest range of 
temperature usually 
experienced, does not 
increase the normal 
mortality among the 
larvse. 
LENGTH OF TIME REQUIRED 
FOR DEVELOPMENT. 
During the warmest 
Hawaiian we ather , 
when the mean tem- 
perature averages about 79.5° F., the Mediterranean fruit fly requires 
as few as 17 or as many as 33 days to pass through its immature stages. 
Fig. 10.— Three important edible fruits subject to fruit-fly attack: 
a, Strawberry guava; b, loquat; c, star apple. These are grown also 
for their ornamental value. (Original.) 
