138 
Psyche 
[June 
might eventually be profitable to explore modifications of the tem- 
perature-summation method in connection with alate development 
both in nature and in controlled environments, and then to relate 
results to the initiation of the flight season. However, the list of 
unknowns concerning this species is so great — location and environ- 
ment of the nest, favorable temperature ranges for the development 
of any caste, etc. — that meaningful calculations are hardly possible 
at present. The simplest and perhaps most plausible explanation for 
the termination of the flight season might lie in the fact that all 
alates had flown. 
Figure 3 shows the flight periods in relation to the following daily 
temperatures during the season in 1962; minimum, maximum and 
temperature 15 minutes after sunset. Daily flight periods (29 in 
1962, 11 in 1963) occurred on days with a mean minimal tempera- 
ture of 20 . 1 ° (range, 12.0 — 24.8) in 1962, and 19.O 0 (range, 13.7 
— 22.0) in 1963. The mean maximal temperature for the same days 
was 33. 3 0 (range, 26.9 — 37-6) in 1962, and 32. 3 0 (range, 29.5 — 
36.7) in 1963. Flights began each day at approximately 15 minutes 
after sunset; the mean temperature for this time, on the days when 
flights occurred, was 28.2° (range, 23.4 — 32) in 1962, and 26.O 0 
(range, 23.7 — 29) in 1963. Within these limits there is no readily 
apparent relation to daily temperature patterns. 
The temperature cycle of a “typical day,” together with curves 
Figure 3. Flight dates of Paraneotermes simplicicornis in relation to 
daily temperature fluctuations in Tucson, Arizona, in 1962. Flights began 
at approximately 15 min. after sunset. Rain or wind may have prevented 
flights on at least 15 evenings. 
