PARADOXICAL POST-COUPLING COURTSHIP 
IN HIMANTIGERA NIGRIFEMORATA 
(DIPTERA, STRATIOMYIDAE) 
By William G. Eberhard 
Smithsonian Tropical Research Institute 
and 
Escuela de BiologU, Universidad de Costa Rica 
Ciudad Universitaria, Costa Rica 
If the function of male courtship behavior is to inform the female 
of a male’s species identity, or to otherwise induce her to allow 
mating to occur, then continuation of courtship after copulation has 
begun would seem to be non-functional. Such post-coupling court- 
ship does occur in some species, however (see summary in Eberhard 
1985, also Loher and Renee 1978, Speith 1984, Longair et al. 1987, 
Goldsmith 1987, Mora 1987, Wcislo in prep.). It might be argued 
that post-coupling courtship is selectively trivial, perhaps a sort of 
overflow that results from high excitement levels in males. On the 
other hand, male courtship behavior could be selectively important, 
serving to induce females to perform key additional reproductive 
processes such as allowing copulation to proceed until semen 
transfer is complete, transporting sperm to storage sites, oviposit- 
ing, rejecting additional suitors, etc. The possibility that such “cryp- 
tic female choice” (Thornhill 1983) occurs after copulation begins 
has substantial theoretical significance, and a general theory 
explaining the rapid and divergent evolution of animal genitalia 
(Eberhard 1985) relies on the supposition that post-coupling court- 
ship is often performed by the male’s genitalia. This paper reports 
observations suggesting that post-coupling female choice is indeed 
selectively important in the stratiomyid fly Himantigera nigrifemo- 
rata (Macquart). 
Materials and Methods 
All flies were observed between 10:00 and 14:00 on sunny or 
partly cloudy days between June and September 1987 in early 
second growth near San Antonio de Escazu, San Jose Province, 
Costa Rica. Small piles of recently cut weedy vegetation were used 
to attract flies. Fifteen copulating pairs were observed. In some 
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