140 
Psyche 
[June 
Figure 4. Relationship between approximate flight time (sunset plus 15 
min.) of Paraneotermes simplicicornis and temperature, relative humidity, 
saturation deficit and evaporation. June 20 was taken as a typical day 
during the 1962 flight season in Tucson, Arizona. 
In relation to daily fluctuations of relative humidity, individual 
flight periods (29 in 1962, 11 in 1963) occurred as follows: on days 
with a mean minimum humidity of 45.8% (range, 37 — 65) in 1962, 
and 47.4% (range, 30 — 65) in 1963; on days with a mean maxi- 
mum humidity of 85.9% (range, 62 — 100) in 1962, and 91.4% 
(range, 65 — 100) in 1963. Mean humidity at flight time (sunset 
plus 15 minutes) was 56.8% (range, 38 — 92) in 1962, and 71.3% 
(range, 36 — 100) in 1963. 
When the rains begin, usually in July, fluctuations in relative 
humidity vary widely during each day as well as from day to day. 
There were several days during the two years studied when the 
relative humidity at the time of sunset was at or close to 100%. 
Daily flights of Paraneotermes almost never occurred on such days; 
indeed, probably as a result of its avoidance of rain, it rarely flew 
