Leona’s little blue (Philotiella leona)
(Lycaenidae: Polyommatinae: Polyommatini)
Profile prepared by Sarina Jepsen and Blake Matheson, The Xerces Society for Invertebrate Conservation
Leona’s little blue butterfly (Philotiella leona) is in imminent danger of going extinct. After two years of comprehensive surveys, Leona’s little blue is known only from a single population of 1,000-2,000 individuals that encompasses less than a six square mile area of the Antelope Desert in Klamath County, Oregon. This highly endemic species occupies a specialized niche within a volcanic pumice and ash ecosystem primarily on unprotected, non-federal timberland, near the town of Chinchalo. A small portion of the population occurs on the Winema National Forest. Because of Leona’s little blue’s single population, high degree of endemism and limited distribution, immediate protection of known and appropriate, contiguous habitat will be necessary for the survival of the species.
This minute butterfly is threatened by conifer encroachment, catastrophic and controlled fire, timbering activities, insecticide and herbicide use, cinder mining, livestock grazing, and, potentially, by a change in land management that will occur when the majority of its habitat changes ownership.
Xerces Red List Status: Critically Imperiled Other Rankings: Canada – Species at Risk Act: N/A Canada – provincial status: N/A Mexico: N/A USA – Endangered Species Act: None USA – state status: S1 NatureServe: G1 IUCN Red List: N/A
Adult Leona’s little blue (Philotiella leona) was discovered in 1995 by Harold and Leona Rice and formally described in 1999 by Hammond and McCorkle. Measuring less than three quarters of an inch, Leona’s little blue is a small and charismatic butterfly. While Leona’s little blue is the largest species of the tiny genus Philotiella, it is noticeably smaller than any of the other blue butterflies with which it co-occurs, including the Glaucon blue (Euphilotes glaucon oregonensis) and the Lupine blue (Plebejus lupini). For a complete description of this species, see Hammond and McCorkle 1999. Hammond and McCorkle’s description is summarized here: the forewings of this species measure 9-12 mm in length. The adult male’s dorsal wings are colored blue, with blackish margins. The adult female’s dorsal wings are black with brownish hues. The ventral hind wing of Leona’s little blue is striking white with prominent black discal and median spots. The spots on the ventral forewings are elongated or rectangular in shape, and slightly larger than the spots on the ventral hind wings. The wings are somewhat narrow and elongated. (Hammond and McCorkle 1999).
Larva and pupa The caterpillar life stage of Leona’s little blue is typically pinkish, or more rarely, green in color and can be found on the larval host plant (spurry buckwheat, Eriogonum spergulinum) from 2-6 weeks after the adult flight period begins. This species overwinters in the pupal stage. (Ross 2008).
The flight period of adult Leona’s little blue generally occurs from mid-June through early July. Both male and female Leona’s little blue have been observed nectaring on sulphur flower buckwheat (Eriogonum umbellatum) (Ross 2009) and a weedy species of Epilobium (Family: Onagraceae) that looks somewhat similar to spurry buckwheat (Hammond and McCorkle 1999). Leona’s little blue adults have also been observed nectaring on its larval host plant spurry buckwheat (S. Jepsen, personal observation, 6 July 2009). Females are less active fliers than males and spend long periods sedentary on vegetation with wings closed. Both sexes exhibit very low-flying flight patterns. Generally, this habit of low flight combined with their tiny size, dark outward cast and sedentary nature renders Leona’s little blue difficult to observe in the field (Hammond and McCorkle 1999).
The explosion of Mt. Mazama (now Crater Lake) approximately 6,600 years ago deposited deep fields of ash-pumice on the eastern slope of the Cascade Range; these xeric habitats host a unique butterfly fauna (Hammond 1983), including the rare Moeck’s fritillary (Speyeria egleis moecki) (Hammond and Dornfield 1983). Leona’s little blue butterfly is endemic to a 6 square-mile area of volcanic ash-pumice habitat within the Antelope Desert of southern Oregon. Its habitat is approximately 9 miles east of Crater Lake National Park, and directly west of U.S. Highway 97, near Sand Creek in Klamath County. Leona’s little blue butterfly occurs primarily in openings of lodgepole pine-bitterbrush forests with abundant spurry buckwheat (Eriogonum spergulinum). The species has been found on a small area of public land within the Winema National Forest, although most occurrences have been documented on private land, owned and managed by Cascades Timberlands LLC.
As discussed below, these forest openings are threatened by conifer encroachment and decades of fire suppression. The habitat is physically disturbed by cinder pit mining, heavy equipment used in timbering operations, and livestock grazing. Pesticide use on the nearby Klamath Marsh and adjacent private lands may drift to contaminate Leona’s little blue habitat.
The type locality for Leona’s little blue butterfly is an area of open ash-pumice land along a vegetated shoulder of U.S. Highway 97, near Sand Creek in Klamath County of south-central Oregon. This area falls roughly between the town of Chinchalo on the east and part of the Winema National Forest to the west, approximately 9 miles east of Crater Lake National Park. Since the discovery in 1995, thorough surveys (including exhaustive searches in the summers of 2008 and 2009), have established that the known range of Leona’s little blue covers only six square miles (Ross 2008 and 2009). The north-south limits of the species’ range run roughly from milepost 225 to milepost 230 on U.S. Highway 97. The majority of observations of the species have occurred near stretches of bare ground on the Mazama Tree Farm, presently held by Cascade Timberlands LLC. This habitat is scheduled for transfer to the Klamath Tribes (made up of the Klamath, Modoc and Yahooskin tribes) once funds for the Klamath Basin Restoration Agreement are appropriated by Congress. The heart of the species distribution is centered roughly on a power line road directly west of Sand Creek Station. In 2008, two occupied sites were found just within the borders of the Winema National Forest, north of NFD Road 6602. In 2009, Leona’s little blue was observed at two additional adjacent locations on the Winema National Forest (Ross 2009). There is also a small parcel of land managed by the Oregon Department of Transportation within this 6 square mile area where Leona’s little blue has been found. This constitutes the entire known global distribution of Leona’s little blue.
Dana Ross, who led the 2008 and 2009 surveys, notes that this species only has one population, consisting of an estimated 1,000 to 2,000 individuals (Ross 2008). It is unknown whether this population is stable or declining, since it has only recently been discovered and population estimates from multiple years are not available. It is possible, but unlikely, that Leona’s little blue may also occur in the volcanic highlands of Northeastern California, where spurry buckwheat is common. There are no records of Leona’s little blue from California, despite the fact that numerous hobby butterfly collectors have frequented these areas (pers. comm. D. McCorkle, 7 Dec. 2009). In 2009, Dana Ross spent 10 days surveying ash-pumice habitats north, east and south of the known population in Oregon with abundant spurry buckwheat, but no additional populations outside of the 6-mile range established in 2008 were documented (pers. comm. D. McCorkle 3 Nov. 2009). Leona’s little blue appears to favor open habitat types where spurry buckwheat can flourish. Extensive surveys of potential habitat in surrounding areas did not expand the known range of Leona’s little blue illustrated above.
Courtesy of Butterflies and Moths of North America, Big Sky Institute.
Leona’s little blue is threatened by conifer encroachment, catastrophic and controlled fire, timbering activities, insecticide and herbicide use, cinder mining, livestock grazing, and, potentially, by a change in land management that will occur when the majority of its habitat changes ownership.
Conifer Encroachment Fire suppression over the past half century has led to a loss of meadow and other open canopy habitat. At present, young lodgepole pine trees are encroaching into numerous open patches of spurry buckwheat and other low-growing shrubs in the heart of Leona’s little blue’s habitat (S. Jepsen, pers. obs., 6 July 2009). Unless addressed, the encroachment of conifers, and subsequent loss of open canopy habitat required by spurry buckwheat, poses a major threat to the survival of Leona’s little blue. To ensure the survival of Leona’s little blue in an actively managed forest, plans should be developed to selectively and carefully manage the encroachment of conifers in the open areas where the butterfly occurs. These plans need to be specific to each site and managers should consult with experts to determine how to manage these areas without further harming this species.
Fire Fire suppression frequently causes extensive changes in forest structure. These changes include an increase in combustible fuel loads, increase in tree density, increase in fire intolerant species, and loss of the herbaceous layer as the shrub community matures (Huntziger 2003). Catastrophic fire often occurs as a result. The Mazama Tree Farm is recognized as having high fire danger due to a high density of lodgepole pine (Milstein 2008). Because Leona’s little blue has only a single population and an extremely limited range, a single wildfire in its habitat could lead to the extinction of the entire species.
Due to the importance of fire in maintaining many native ecosystems, the use of controlled burning as a management tool has become increasingly common. Although the effects of fire on vegetation and vertebrate communities are more widely understood than the effects of fire on invertebrates, fire can be detrimental to butterflies if their biology is not considered when designing a fire management strategy (Gibson et al. 1992). A recent study examining the impact of prescribed burning on the mardon skipper (Polites mardon) in Northern California showed that burned areas had an order of magnitude fewer butterflies than areas that were not burned. Burned areas may be re-colonized by butterflies flying in from unburned parts of the meadow, but the rate and extent of this re-colonization for mardon skippers has not been investigated and is currently unknown. If an entire area had been burned, the mardon skipper would likely have been extirpated from the site (Black et al. 2009).
Similar to the mardon skipper, the single population of Leona’s little blue is vulnerable to extirpation from controlled burning. The controlled burning of Leona’s little blue habitat could extirpate the population if not done carefully, with consideration of butterfly behavior and life stage at the time of the burn and knowledge of where the butterfly population is distributed across the burn-site. Since only a single, isolated population of Leona’s little blue exists, there would be no additional source population available to re-colonize a burned area if the Leona’s little blue population was locally extirpated by a fire. The petitioners believe that both wildfires and certain controlled burns pose a major threat to the survival of Leona’s little blue.
Timber Management While some amount of selective timber harvest may benefit Leona’s little blue, since its host plant is an early successional species, the impacts associated with intensified management of the Mazama Forest for timber production may cause a destructive increase of road building, traffic and heavy equipment operations throughout Leona’s little blue’s habitat. Management practices which favor increased stand density may result in the eventual compromise of the sunny, exposed conditions that spurry buckwheat requires. Furthermore, trampling by personnel, piling of log slash, and burning of log piles in Leona’s little blue habitat, if done without consideration of Leona’s little blue distribution and biology, may harm the butterfly.
Insecticide Use Insecticides are commonly used in rangeland areas across south central Oregon to control native grasshoppers. Insecticides are routinely applied to the Klamath Marsh National Wildlife Refuge and nearby private lands, funded in part by the Animal and Plant Health Inspection Service and the Oregon Department of Agriculture. Leona’s little blue habitat is approximately five miles west of Klamath Marsh National Wildlife Refuge, and is less than one mile west of privately owned rangelands that may be sprayed for native grasshoppers.
Insecticides that may be used in rangeland areas in Klamath County, Oregon to control native grasshoppers include: diflubenzuron (Dimilin, an Insect Growth Regulator), carbaryl (carbamate), and malathion (organophosphate). Broad-spectrum insecticides used for grasshopper control in rangelands negatively impact non-target insects (Alston & Tepedino 2000), including butterflies. All pesticides that can be used to control native grasshoppers are highly toxic to all life stages of this butterfly, with the exception of diflubenzuron, which is primarily toxic to the larval stage of Leona’s little blue butterfly.
Pesticide drift Although ATV application is currently the most common application method for killing grasshoppers on the Klamath Marsh National Wildlife Refuge, insecticides are commonly applied aerially throughout the west. If insecticides are applied aerially near Leona’s little blue habitat, the potential for pesticide drift to cause mortality to Leona’s little blue butterflies is great. Drift is the movement of spray droplets or pesticide vapor out of the intended spray area. When pesticides are applied by ground application or by air, the potential exists for off-target movement or drift. Several factors affect how much and where a pesticide will drift, most importantly droplet size and weather. Smaller droplets remain suspended in the air much longer than larger droplets and can thus drift over longer distances. Wind speed and direction, relative humidity, air temperature, and atmospheric stability are weather factors that influence spray drift. During windy conditions, significant amounts of pesticide can drift outside the spray area. Even small amounts of a pesticide can drift great distances under stable weather conditions. This long range drift is often related to the occurrence of a temperature inversion, an atmospheric phenomenon generally associated with stable weather conditions when wind is calm and skies are clear. In these conditions, the air near the surface is cooler than the air above it, resulting in small spray droplets being suspended for longer periods and consequently able to move laterally very long distances in very light wind.
A study from Penn State assessing drift of malathion when used to control boll weevil found that it can drift up to one kilometer (5/8 mile)—the greatest distance measured—from the point of application (Penn State 1993). According to the study, the highest amount of drift at one kilometer occurred when atmospheric conditions were stable, meaning vertical air mass movements were dampened. Two other field studies summarized in the 1997 EPA Registration Eligibility Decision for diflubenzuron (Dimilin) found that it drifted at least 1,200 feet. In Butte County, California, MCPA, dimethyl amine spray drifted 400 meters (1,300 feet) and in Tulare County, California, carbaryl drifted 550 meters (1,787 feet) (Majewski & Capel 1995). A study of carbaryl applications in orchards in Vermont found that aerially applied carbaryl repeatedly drifted to the most distant sampling point (about 500 yards) under all wind and atmospheric stability conditions tested.
Studies show consistently that pesticide drift can be found one kilometer (5/8 mile) from the edge of the spray site and sometimes much farther. In Arkansas, drift of the herbicide propanil was concentrated enough at one kilometer to be injurious to crop plants (Barnes et al. 1987). Ghassemi et al. analyzed six different field studies of insecticide drift using a curve fitting method to estimate the “worst case” and “best case” estimates of deposition over distances up to ten kilometers (6.21 miles) (Ghassemi et al. 1982). Even the best case scenario plotted drift over two kilometers (1.25 miles) and the worse case scenario found that 4.5% of the applied dose of pesticide would drift one kilometer (5/8 mile), 1.7% to two kilometers (1 1/4 miles), 0.38% to five kilometers (3.1 miles), and 0.1% to ten kilometers (6.21 miles). In one of the studies analyzed, carbaryl was found at over 1% of the applied dose over seven kilometers (4.3 miles) from the spray edge (Ghassemi et al. 1982).
In summary, 1) All insecticides used against native grasshoppers are highly toxic to Leona’s little blue butterfly; 2) The areas that are frequently treated are within one mile of Leona’s little blue habitat; 3) Drift from pesticide application has been shown to occur up to many miles from the point of application; 4) The global distribution of this highly endemic butterfly includes only a six-mile area in the Antelope Desert; and 5) Exposure of Leona’s little blue butterfly to any of the insecticides proposed for use against grasshoppers in Klamath County, Oregon could lead to the extinction of this butterfly.
Herbicide Use Herbicides that are commonly used for timber management and restoration projects threaten Leona’s little blue both directly (by harming larvae) and indirectly (by killing its host plant, spurry buckwheat). The broadcast application of a non-selective herbicide can indiscriminately reduce both floral resources and host plants for butterflies (Smallidge & Leopold 1997). A few commonly used herbicides that negatively affect butterflies are discussed below: chlorsulfuron, glyphosate, triclopyr, sethoxydim and fluazifop-p-butyl.
Chlorsulfuron is an herbicide that controls select broadleaf weeds and undesirable grasses. Effects of chlorsulfuron to terrestrial invertebrates have been studied using a leaf beetle (Gastrophysa polygoni), and large white butterfly (Pieris brassicae) (Kjaer & Elmegaard 1996). Direct spray of first-instar larva and feeding of larva on treated plants did not produce significant changes in mortality, but did delay development of those feeding on treated plants. Placing eggs of the leaf beetle on treated plants significantly decreased survival (Kjaer & Elmegaard 1996).
Glyphosate and triclopyr, two other common herbicides, are also identified as potentially problematic for the Oregon Silver Spot butterfly in exposure scenarios (USDA Forest Service 2005). In a laboratory study, Russell and Schultz showed that sethoxydim and fluazifop-p-butyl herbicides both reduce development time of Puget blue (Plebejus icarioides blackmorei) butterflies from the date of treatment to eclosure, and reduce survival, pupal weight, and wing size of cabbage white butterflies (Russell & Schultz 2009). Cinder Mining Numerous cinder pits operated by the Oregon Department of Transportation (ODOT) exist in the vicinity of Leona’s little blue habitat, some of which are on Fremont-Winema National Forest land. ODOT uses volcanic rock material mined from cinder pits to apply to roads for safety in inclement weather. In order to meet demands for material, these cinder pits are periodically expanded. For example, in a recent Schedule of Proposed Actions, the Fremont-Winema National Forest proposed to expand the size of the Lookout Butte and Jackson Creek Cinder Pits on the Chemult Ranger District, which are relatively close to Leona’s little blue habitat (USDA Forest Service 2009). In 2006, a proposal to expand Burnt Butte Cinder Pit was approved – this cinder pit is within a couple of miles of Leona’s little blue’s known habitat. In one case, ODOT summarizes its exploration activities to search for new areas to expand cinder pits as drilling 10-30 holes with truck and track mounted equipment within a 40 acre area adjacent to the pit (University of Oregon Document Archive 2009). The drilling and heavy equipment traffic associated with exploration for new cinder pits, the development of new cinder pits, and the expansion of existing pits, all have a high potential to destroy the habitat and cause direct butterfly mortality.
Change in land management The majority of the six-square mile patch of Leona’s little blue habitat exists on the Mazama Tree Farm, which is presently owned by Cascade Timberlands LLC and scheduled for transfer to the Klamath Tribes once funds for the Klamath Basin Restoration Agreement (KBRA) are appropriated by Congress. Once the land transfer occurs, land management may be incompatible with the survival of Leona’s little blue butterfly. A recent newspaper article reports that the Klamath Tribes may develop a biomass energy facility on the Mazama Tree Farm that would create power by burning wood waste and/or garbage (Milstein 2008). Such a facility, if built on Leona’s little blue habitat, could drive this species to extinction. Also if lodgepole pine trees were intensively harvested for this biomass facility, the associated impacts could further harm this species and its habitat. The Mazama Tree Farm currently has a high density of lodgepole pine trees that pose a risk for wildfire – once the land transfer occurs, the tribes plan to restore the land to a “healthy, productive forest” (Milstein 2008). While a change in timber management practices may ultimately benefit some species, it is possible that land management changes will negatively impact the habitat, and ultimately the survival, of Leona’s little blue. Livestock Grazing The impact of livestock grazing on Leona’s little blue habitat is unknown, but current or future grazing practices may threaten this species. Cattle are non-selective browsers with the capacity to destroy native vegetation (Pickering 1997), such as spurry buckwheat and other plants that Leona’s little blue visits for nectar. Intensive livestock grazing can cause adverse impacts to butterfly populations by (1) trampling eggs, larvae, pupae, and adults and (2) eating larval and adult food sources, and (3) disturbing the soil, which allows weeds to invade (Warren 1993). The Klamath Tribe’s Timber management plan, which will be used once the Mazama tree farm is transferred to the Klamath tribes, allows domestic livestock grazing on winter range if it enhances mule deer habitat (Johnson et al. 2008). Under the current management plan for the Winema National Forest, grazing is allowed within habitat suitable for Leona’s little blue butterfly (USDA Forest Service 1990).
Alston, D.G. and V.J. Tepedino. 2000. Direct and indirect effects of insecticides on native bees. In Grasshopper Integrated Pest Management User Handbook (Technical Bulletin No. 1809), edited by G.L. Cunningham and M.W. Sampson. Washington, DC: United States Department of Agriculture Animal and Plant Health Inspection Services.
Barnes, C.J., T.L. Lavy, and J.D. Mattice. 1987. Exposure to non-applicator personnel and adjacent areas to aerially applied propanil. Bull. Environ. Contam. Toxicol. 39:126-133.
Black, S.H., C. Mazzacano, and L. Lauvray. 2009. Mardon skipper survey of Coon Mountain burn site. Report to the U.S. Fish and Wildlife Service and U.S. Forest Service. The Xerces Society for Invertebrate Conservation.
Brenner, L. 1992. Malathion Fact Sheet. Journal of Pesticide Reform, Volume 12, Number 4, Winter 1992. Northwest Coalition for Alternatives to Pesticides, Eugene, OR.
Cox, C. Carbaryl. Journal of Pesticide Reform, Volume 13, Number 1, Spring 1993. Northwest Coalition for Alternatives to Pesticides, Eugene, OR.
Ehrlich, P.R. 1992. Population biology of checkerspot butterflies and the preservation of global biodiversity. Oikos. 63:6-12
Ghassemi M., P. Painter and M. Powers. 1982. Estimating drift exposure due to aerial application of insecticides in forests. Environmental Science Technology. 16: 510-514.
Gibson C.D., V.K. Brown, L. Losito, and G.C. McGavin. 1992. The Response of Invertebrate Assemblies to Grazing. Ecography 15(2): 166-76.
Hammond, P.C. 1981(83). The colonization of violets and Speyeria butterflies on the Ash-Pumice fields deposited by Cascadian volcanoes. Journal of Research on the Lepidoptera 20(3): 179-191.
Hammond, P.C. and E.J. Dornfeld. 1983. A new subspecies of Speyeria egleis (nymphalidae) from the pumice region of central Oregon. Journal of the Lepidopterists’ Society 37(2), 1983, 115-120.
Hammond, P.C. and D.V. McCorkle. 1999. A new species of Philotiella from the Oregon Cascade Range (Lepidoptera: Lycaenidae). Holarctic Lepidoptera, 6(2): 77-82.
Hanski, I., J. Poyry, T. Pakkala, and M. Kuussaari. 1995. Multiple equilibria in metapopulation dynamics. Nature. 377:618-621.
Huntzinger M. 2003. Effects of fire management practices on butterfly diversity in the forested western united states. Biological Conservation, 113(1): 1-12. Johnson, K.N., J.F. Franklin, and D.L. Johnson.
May, 2008. A Plan for the Klamath Tribes’ Management of the Klamath Reservation Forest. 225 pages. Accessible online: http://www.klamathtribes.org/information/background/documents/Klamath_Plan_Final_May_2008.pdf, last accessed 3 December 2009.
Kjaer, C. and N. Elmegaard. 1996. Effect of herbicide treatment on host plant quality for a leaf-eating beetle. Pesticide Science. 47(4) 319-325. Majewski M. and Capel P. 1995. Pesticides in the Atmosphere: Distribution, trend and governing factors, Ann Arbor Press, Inc. Chelsea MI.
Martinat, P. J., V. Christman, R. J. Cooper, K. M. Dodge, R. C. Whitmore, G. Booth, and G. Seidel. 1987. Environmental fate of dimilin 25-W in a central Appalachian Forest. Bulletin of Environmental Contamination and Toxicology. 39:142-149.
Milstein, M. December 18, 2008. Land Deal Returns Slice of Klamath Tribal Homeland. The Oregonian. Accessible online: http://www.oregonlive.com/environment/index.ssf/2008/12/land_deal_returns_slice_of_kla.html, last accessed 2 December 2009 Pelham, J.P. 2008. A Catalogue of the Butterflies of the United States and Canada. The Journal of Research on the Lepidoptera. Volume 40, 658 pages.
Penn State. 1993. Study of off site deposition of malathion using operational procedures for Southeastern cotton boll Weevil eradication program. Aerial application technology laboratory. Department of Entomology.
Pickering, D.L. 1997. The influence of fire on west coast grasslands and concerns about its use as a management tool. A case study of the Oregon silverspot butterfly Speyeria zerene hippolyta (Lepidoptera, Nymphalidae). Pages 37-46 In Proceedings of fire effects on rare and endangered species and habitats conference in Coeur d’Alene, Idaho. 1995.
Pyle, R.M. 2002. The Butterflies of Cascadia. Seattle Audubon Society, Seattle, WA. 420 pages.
Robertson J.L. and L.M. Boelter. 1979. Toxicity of insecticides to Douglas-fir tussock moth. Residual toxicity and rainfastness. Canadian Entomology. 111: 1161-1175.
Ross, D. 2008. Surveys for Leona’s little blue (Philotiella leona) in the Antelope Desert of Klamath County, Oregon. A report to High Desert Museum (Bend, OR) and USFWS (Portland, OR). 10 pages.
Ross, D. 2009. 2009 Surveys for Leona’s little blue (Philotiella leona). A report to The Xerces Society and U.S. Fish and Wildlife Service. 22 pages.
Russell, C. and C.B. Schultz. (2009). Effects of grass-specific herbicides on butterflies: an experimental investigation to advance conservation efforts. Journal of Insect Conservation. Online publication date: 29 May 2009.
Sample, B. E., R. J. Cooper, and R. C. Whitmore. 1993 Dietary Shifts among Songbirds from a Diflubenzuron-Treated Forest. Condor. 95: 616-624.
Schultz, C.B. 1998. Ecology and Conservation of the Fender’s Blue Butterfly. PhD. Dissertation, University of Washington. Seattle, WA. 145pp.
Shaffer, M.L. 1981. Minimum Population Sizes for Species Conservation. BioScience 31(2): 131-134. Smallidge P.J. and D.J. Leopold. 1997. Vegetation management for the maintenance and conservation of butterfly habitats in temperate human-dominated habitats. Landscape and Urban Planning 38: 259-280.
Thomas, C.D. and S. Harrison. 1992. Spatial dynamics of a patchily distributed butterfly species. Journal of Animal Ecology. 61:437-446. University of Oregon Document Archive. 2009. Accessible online: https://scholarsbank.uoregon.edu/xmlui/handle/1794/6906, last accessed 1 December 2009.
USDA Forest Service, Pacific Northwest Region. 1990. Winema National Forest Land and Resource Management Plan. Accessible online: http://www.fs.fed.us/r6/frewin/projects/forestplan/index.shtml, last accessed 3 December 2009.
USDA Forest Service. April 2005. Preventing and managing invasive plants: Final Environmental Impact Statement. Pacific Northwest Region. 173 pages.
USDA Forest Service. 2009. Accessible online: http://www.fs.fed.us/r6/frewin/projects/sopa/20091008-chemult.pdf, last accessed 1 December 2009.
Warren MS. 1993. A review of butterfly conservation in central southern Britain: II. Site management and habitat selection of key species. Biological Conservation. 64: 37-49.
Big Sky Institute, Butterflies and Moths of North America: Pumice Dotted-Blue (Accessed 4/22/10)
NatureServe Explorer(Accessed 4/22/10)