The Dakota skipper Hesperia dacotae and the Poweshiek skipperling Oarisma poweshiek (Hesperiidae) are imperiled univoltine prairie obligate butterflies native to the north-central USA and southern Canada, and ex situ conservation strategies have been identified as important tools for their recovery. Understanding the reproductive behaviors of these taxa is crucial for maximizing their reproductive potential and the efficacy of these conservation activities. It is generally assumed that, within Lepidoptera, females preferentially oviposit on substrates that are most suitable for the development of their offspring, but this has been shown to not always be true. Here, we examined whether Dakota skipper and Poweshiek skipperling females exhibited oviposition substrate preferences for 3 potential larval host graminoids: prairie dropseed Sporobolus heterolepis, tussock sedge Carex stricta, and smooth brome Bromus inermis. Our results suggest that, at least in an ex situ setting, Dakota skippers and Poweshiek skipperlings preferentially oviposit on graminoids over abiotic substrates, and both taxa demonstrate a stronger preference for prairie dropseed over tussock sedge and smooth brome. These results will better inform continued ex situ management and have important in situ implications, as these skippers may oviposit on invasive grasses (i.e. smooth brome in our experiment) despite the presence of more suitable host plants.

The Poweshiek skipperling Oarisma poweshiek (Parker, 1870) (Lepidoptera: Hesperiidae) is an endangered prairie obligate butterfly native to the north central United States and southern Canada. Conservation efforts for this species rely on ex situ approaches for population augmentation and reintroductions. As such, improving our understanding of the behaviors of Poweshiek skipperlings and maximizing their reproductive output in an ex situ setting are critical for the success of associated conservation initiatives. In this study, we examined the frequency of breeding behaviors exhibited by Poweshiek skipperlings in relation to various environmental factors: sunlight intensity (measured in lux), ambient temperature, and age. Sunlight intensity was a significant predictor of breeding behavior frequency, but we did not detect an effect of ambient temperature on breeding behavior. We also documented a generally negative relationship between age and breeding behavior frequency for both sexes. The results of our study underscore the importance of natural sunlight in encouraging breeding behaviors in an ex situ conservation environment. Ex situ observations also can help identify environmental conditions that promote high levels of Poweshiek skipperling activity, which could be used to optimize the timing of in situ population surveys.