fire management used on prairie lands can negatively affect the regal fritillary. Powell et al. (2006) examined the effects of prescribed prairie burns by surveying a number of prairies in Kansas. Butterflies were observed on both recently burned and unburned sites to determine the effects of prescribed burning on the populations. Population density of the regal fritillary may tend to vary among sites but was generally considerably higher at sites that had not been burned in the past year (Powell et al. 2006). Prescribed burns are usually conducted in the early spring when the first instar larvae are vulnerable, buried in the leaf litter. Extensive prairie burns kill the overwintering larvae and can have a drastic effect on their population in the following years. One recently burned prairie that was studied used minimal patch burning, burning only small portions of the entire area at a time. This site had by far the highest regal fritillary abundance of any burned site (Powell et al. 2006). A serious potential threat to the regal fritillary was discovered in a captive breeding study. Wagner (1995) found that disease is a possible mortality factor in some S. idalia populations. In a captive group, nuclear polyhedrosis virus (NPV) caused an 80% loss. The virus is transmitted from females to offspring in eggs or between individuals through excreta (Wagner 1995). NPV could potentially be damaging to populations in the wild (Mason 2007); thus, for reintroduction purposes, culturing a virus-free line is critical. The regal fritillary is highly vulnerable to environmental factors year-round. Extreme weather conditions over a large geographical range can severely influence their populations. First instar larvae are highly sensitive to extreme weather conditions as they overwinter in the leaf litter and as they begin their search for food plants in the spring. Hard frosts late in the spring, severe storms, and cool damp conditions have all been shown to negatively impact larvae survival (Selby 2007). Larval development rates tend to be proportional to the temperature. Therefore, unusually cool conditions in the spring can drastically slow larval growth rates, increasing their exposure to mortality factors (Selby 2007). Some environmental factors can limit adult regal fritillary activity as well. Prolonged periods of cooler temperatures, cloudy skies, and rain can restrict normal activities, perhaps limiting reproduction (Selby 2007). The increased use of pesticides and herbicides can have profound negative effects on the regal fritillary as well. Heavy spraying