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Studies of at-risk species are likely to have greater conservation impact if they: involve managers in question formulation, set specific management or restoration goals, and are based on detailed knowledge of species’ resource needs. These ideas guided our investigation of the foraging behavior of larvae of a US federally threatened butterfly, the Oregon silverspot (Speyeria zerene hippolyta), with the goal of making management recommendations for habitat restoration. S. z. hippolyta larvae feed exclusively on Viola adunca and must consume multiple individuals to pupate successfully. Larvae forage at random through meadow vegetation to locate host plants. Observations of larvae foraging under field conditions revealed that larger, older larvae move more rapidly and turn less acutely than smaller, younger larvae; the consequence of these developmental differences is that younger larvae tend to remain in one place while older larvae tend to range more widely, presumably in search of new host plants. Results from a simulation model initialized with these data suggested that a host plant density of at least four V. adunca plants/m2 (depending on predation intensity to which larvae are exposed) is required in order for 4th instar larvae to have a 10 % chance of survival to pupation. These findings are being used to guide a violet restoration program for this sensitive species.

The genetic structure of lineages can provide important information for delineating “evolutionarily significant units” (ESUs) for conservation, and for planning actions to protect and restore taxa threatened with extinction. Speyeria zerene hippolyta, the Oregon silverspot butterfly, is a U.S.A. federally threatened subspecies that is the focus of considerable conservation effort, but whose evolutionary relationships with other Speyeria taxa are not well-understood. We conducted a genetic analysis of nine Speyeria species and 25 subspecies from western U.S.A., using both mitochondrial and nuclear markers. Our goal was to determine whether such data supported (a) S. z. hippolyta’s designation as an ESU, and (b) the current morphologically-based taxonomy of Speyeria spp. Our data for S. z. hippolyta were equivocal; while nuclear markers resolved all these individuals into a single clade, mtDNA data suggested the existence of two clades. Aside from S. cybele, which was consistently supported as monophyletic, our data provided little support for most of the species currently recognized for western U.S. Speyeria, including S. zerene, and even less for the many subspecies designations. These genetic findings stand in contrast to the morphological differences recognized by experts, and suggest a relatively recent origin for many of these taxa. Two of 66 individuals screened for Wolbachia infection tested positive for this symbiont. Our results provide no persuasive evidence that S. z. hippolyta should lose its status as an ESU, but they have important implications for ongoing management actions such as population augmentation.