128 
Psyche 
[March 
T f (minutes) 
Fig.l. Frequency distribution of Tf in Poanes hobomok. 
tions in this species have ranged from a low of IOO minutes to a 
high of 12 (± 3) hours (T. E. Pliske, personal communication). 
A pyrgine skipper butterfly, Erynnis tristis, copulated for a little less 
than one hour (Shields 1968). 
Data reported below were obtained in the course of genetically 
analyzing sex-limited wing-color dimorphism in a hesperiine skipper, 
Poanes hobomok (Burns, unpublished). All material used in this 
work came from southern New England: Rockfall and Portland, 
Middlesex County, Connecticut; vicinity of Mt. Tom, north of 
Holyoke, Hampden County, Massachusetts; and Jacksonville, Wind- 
ham County, Vermont. Although, in nature, P. hobomok is univoltine 
and spring-flying, a second generation was forced in late summer 
by laboratory rearing. On sunny days in August and September at 
Middletown, Connecticut, reared virgins were placed in outdoor 
screen cages, large enough (60" long X 28" wide X 39" high) to 
permit fl:ght, and were continuously watched. Copulations were 
timed from beginning to end, with the result shown in Table 1. 
The Tf s are normally distributed around a mean of 38 1/4 min- 
utes (fig. 1). In view of their considerable length, the T f s are 
remarkably consistent. 
Males of P. hobomok are monomorphic but females are dimorphic: 
one female morph (light) is similar in facies to the male whereas 
the other (dark) is not. Seven experimental crosses involved light 
females and six, dark ones. Female color-pattern did not significantly 
affect Tf. Nor did the time of summer at which crosses occurred, 
later crosses not being significantly longer than earlier ones. 
In general, T f , like so many behavioral phenomena, is best ap- 
proached statistically, with due regard, however, for prevailing 
weather conditions. Casual observations suggest that cloudiness and 
lower temperatures tend to prolong T f , which is not surprising. 
Presumably it cannot be shortened indefinitely because of the logistics 
of spermatophore production. 
