62 
Psyche 
[March 
Temporal distribution. — Both limpia and nessus are multivoltine, 
and both fly at the same times. Nearly all of the dated wild-caught 
adults of Celotes that I examined were collected from March to 
September: in Texas, every half-month interval from the beginning of 
March to mid-September includes records of both limpia (N = 68) 
and nessus (N = 1 58 ) ; however, for Arizona nessus (N = 183), 
the months of May and June together yield but 3 records, which 
leaves a major gap between one large cluster of records in March 
and April and another in July, August, and the first half of Septem- 
ber. The only other dated wild-caught specimens examined are 5 
nessus from far southern Arizona collected in mid-January and 
5 nessus from the last half of September and the first half of October 
from central and, as might be expected, extreme southern Texas (the 
lower Rio Grande Valley). In the experience of Kendall (1965), 
nessus flies from early March to mid-November in Texas. 
The fact that temporal distribution is essentially continuous 
through the warm season for both limpia and nessus in Texas but 
distinctly bimodal for nessus in Arizona probably relates to the dif- 
ferent patterns of rainfall in the two states. For the most part, 
Texas has much more evenly distributed precipitation than does 
Arizona, where it occurs in two widely disjunct winter and summer 
periods. The second flight period of nessus in Arizona coincides with 
the summer rainy season, to which it is presumably geared. In the 
course of his field studies and laboratory rearings, Kendall (1965, 
and unpublished) has observed that full-grown larvae of Celotes are 
able to enter diapause (facultatively) to beat heat and drought, as 
well as to get through the cold of a winter season. Kendall has 
shown in the laboratory that such diapause can be broken by pro- 
viding moisture, whereupon larvae pupate and produce adults 
promptly. Given this capacity to be flexible, variable larval growth 
rates, and the usual vicissitudes of weather, individuals of a single 
generation must often get out of synchrony with the result that gen- 
erations overlap broadly and irregularly, forming no definite number 
per year in either species. 
There are no indications that limpia and nessus are temporally 
displaced with respect to each other where they spatially coexist in 
Trans-Pecos Texas. Rather, my records show that adults of both 
species have repeatedly been collected in association — unwittingly, 
of course, since the collectors were unaware of the existence of more 
than one species of Celotes. On nine occasions altogether, five dif- 
ferent collectors (or pairs of collectors) have caught a total of 37 
