"For a sexually reproducing animal to pass its genetic information on to the next generation, it must first find a mate. In many animal species, males advertise themselves to attract females. In addition to attracting a mate, male advertisements can also draw in predators and parasitoids (reviewed in Zuk and Kolluru, 1998). Selection for female response to male advertisement may therefore occur together with selection for avoidance of predators and parasitoids (Zuk et al., 2006). There are abundant data showing that males increase their risk of predation or parasitization through mating behaviors (reviewed in Zuk and Kolluru, 1998). Less is known about the risks to females. My study will address whether the risk of a female being parasitized also increases during copulation.Anasa tristis, the squash bug, is parasitized by a fly, Trichopoda pennipes. Fly females are attracted by squash bug male advertisement pheromones (Aldrich et al., 2006). Flies lay their eggs on both male and female squash bugs on the surface of their abdomen. This parasitization is fatal. Laboratory trials show that male and female squash bugs are less likely to copulate with a parasitized individual (Hamel, pers. comm.). In contrast, field data show that parasitized and non-parasitized females are equally likely to be found copulating (Hamel and Miller, unpub.) Because copulations can be long (mean= 76.40 min, range: 34.00-118.97 min, n=10 pairs) (J.Hamel unpub), one possibility that reconciles these contradictory field and laboratory findings is that females may be parasitized during copulation. If this is true, this suggests that copulation may be costly to females, and that parasitoid presence should select for fewer and shorter copulations. I will first investigate whether A. tristis females are more likely to be parasitized by T. pennipes during copulation. I will observe parasitoid flies and squash bug males and females in semi-natural field enclosures. Each enclosure will contain an equal number of marked female and male A. tristis and several parasitoid flies. My response variables will include the time and behavioral context in which each squash bug is parasitized. I will also note if copulating A. tristis males and females are parasitized. If T. pennipes lays eggs on copulating pairs more often than on solitary female squash bugs, we can suggest that copulation is costly to squash bug females. Finally, I will assess if squash bug copulation duration differs according to whether parasitoids are absent or present. To do this, I will compare copulation durations of squash bugs in parasitoid-free enclosures with those of bugs in enclosures with parasitoids.I will collect both A. tristis and T. pennipes from the field. I will gather A. tristis as juveniles, to ensure they have not previously mated, and I will rear both species in growth chambers. My mentors in the Miller Laboratory have successfully collected and reared these species. I will begin to work on this project in spring 2013 for ten hours each week, continue research during summer 2013 for thirty hours each week, analyze my data the following fall 2013, and complete my project spring 2014. If my data support my hypothesis, this provides a contribution to sexual selection theory. Current theory suggests that males usually bear the cost of attracting predators and parasitoids (reviewed in Zuk and Kolluru, 1998). If my data do not support my hypothesis, an alternative hypothesis is that recently parasitized females may become less choosy about potential mates, and therefore be more likely to accept copulations. In summary, this research project adds to existing knowledge on whether parasitoids can exert selection on copulation behavior.