Pollinator Habitat Conservation Along Roadways, Volume 4: Great Basin (2023)

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3-1 Chapter 3 Imperiled Pollinator Profiles The Great Basin is home to a diverse assemblage of pollinators. Here we define the Great Basin to include parts of Nevada, Utah, Idaho, and Oregon (Figure 1-1). In this region, there is one species listed under the federal Endangered Species Act (ESA), and one candidate species as of March 2022. However, there are many imperiled pollinators in this region that are not protected by the ESA. This chapter provides profiles of ESA listed and candidate pollinator species found in the Great Basin, as well as imperiled pollinators that have the potential to be listed in the future based on NatureServe rankings and expert opinion (Table 3-1). The profiles of imperiled species not listed under the ESA include four imperiled bumble bees, and one imperiled butterflies. This is not an exhaustive list of all declining pollinators in the region; the focus is on species in need of conservation that have a broad distribution and those that are more likely to impact Departments of Transportation. An overview of the basic biology of bees, butterflies, and other insect pollinators can be found in Chapter 2. This section presents information on life history, distribution, threats, and habitat requirements for imperiled pollinators in this region. Information on known adult flight times (i.e., the breeding period) and larval active times (for butterflies and moths; larval bees live within nests) are included. The profiles also include a list of important plants that are used by each species as host plants or for pollen and/or nectar. Some of these plants are nonnative species or noxious weeds. These species are included in the profiles, as the information may be useful, but using them in revegetation efforts is not recommended (see Chapter 7 for more). Some basic conservation recommendations and information on the effects of roadside management on each species are also provided, when such information is available. Insects generally tend to be less well studied than vertebrates; therefore, very little is known about the biology and habitat requirements of some of these species. Other pollinator species may be better studied, but rigorous studies of the effects of different management practices on the species or their habitat may still be lacking. The best possible recommendations are made based on the available information. The profiles provide information on life cycles, host plants, habitat needs, and adult flight times that can be used to tailor maintenance and revegetation decisions (Chapters 6 and 7). General active times for adults and larvae are also provided. It should be noted that active times may shift regionally, such as with elevation or latitude, or from year to year with changes in climate. However, consultation with local experts, as well as biologists from state and federal agencies, is recommended to help DOTs develop meaningful management plans for species of interest in their areas because the profiles cannot capture the site- specific nuances that should be considered. As the profiles indicate, habitat loss is a primary driver of species’ declines. Roads can be a source of habitat fragmentation (Box 5-3). However, with investments in high-quality revegetation (revegetation that prioritizes usage of native plants and high plant diversity, including an abundance of flowering plants that provide pollen and nectar or act as host plants for butterflies) where appropriate, roadsides also provide an ideal opportunity to increase habitat connectivity for many species, including pollinators. It is important to note

Chapter 3. Imperiled Pollinator Profiles  3-2 that although some of the species profiled in this section may be unlikely to use roadside habitat for breeding, individuals may still use roadside habitat for nectar or pollen or as movement corridors. Therefore, it is worthwhile to invest in high-quality habitat restoration projects along roadsides near natural areas, preserves, and populations of imperiled species. Another common threat to many imperiled butterflies in the United States is noxious and invasive plants that displace required host plants. Here again, investing in high-quality habitat restoration using native plants can benefit imperiled pollinators, even if those pollinators are not using roadside habitat, by helping to slow the spread of invasive plants into key habitat areas. This section includes profiles of pollinator species that may not occur in roadside habitat, but may be found in other DOT land holdings, such as mitigation areas (Table 3-1). Table 3-1. List of profiled imperiled pollinator species in the Great Basin region. Scientific Name  Common Name  Status#  ESA‐Listed Pollinator Species  Danaus plexippus   Monarch butterfly  Candidate  Pseudocopaeodes eunus obscurus  Carson wandering skipper  Endangered  Declining Pollinator Species  Bombus fervidus  Yellow bumble bee  G3G4  Bombus morrisoni  Morrison’s bumble bee  G3  Bombus occidentalis*  Western bumble bee  G3  Bombus suckleyi*  Suckley’s cuckoo bumble bee  G2G3  Callophrys sheridanii ssp.  Desert green hairstreak  G5T3T4  * Species under review or on the USFWS workplan to be evaluated for listing under the ESA as of March 2022. # Status of pollinators is either the ESA status for listed species or is taken from NatureServe (accessed  March 2022) for species not listed under the ESA.    G1: Critically Imperiled. At very high risk of extinction due to extreme rarity (often five or fewer populations), very steep declines, or other factors.  G2: Imperiled. At high risk of extinction due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors.  G3: Vulnerable. At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors.  G4: Apparently Secure. Uncommon but not rare; some cause for long‐term concern due to declines or other factors.  G5: Secure. Common; widespread and abundant.  G#G#: Range Rank. A numeric range rank (e.g., G2G3) is used to indicate the range of uncertainty in the status of a species or community.  T#: Infraspecific Taxon (for subspecies or varieties). The status of infraspecific taxa is indicated by a “T‐ rank” following the species’ global rank. For example, the global rank of a critically imperiled subspecies of an otherwise widespread and common species would be G5T1.

Chapter 3. Imperiled Pollinator Profiles  3-3 3.1 Monarch Butterfly (Danaus plexippus)  Jan  Feb  Mar  April  May  June  July  Aug  Sept  Oct  Nov  Dec  Adult  Larvae  Adult monarch (top left) and monarch distribution within the United States. (top right). Adult flight times  (i.e., breeding period; blue) and larvae active periods (green) for monarchs in this region are shown in the  chart (bottom). Adult and larval active times vary regionally; see Figure 3‐1 for regionally specific suggested  management windows. Photo credit: Stephanie McKnight/The Xerces Society.  Order: Lepidoptera Family: Nymphalidae Status: Candidate Distribution: As of 150 years ago, the monarch was restricted to southern Canada, the lower 48 states, Mexico, Central America, and northwestern South America. In recent years the species has spread or been introduced to other areas including Spain, Hawaii, Australia, and New Zealand. Where it occurs: During the breeding season, monarchs can be found in terrestrial habitats throughout the western United States, but they tend to avoid dense forest. How to recognize: Orange and black monarchs are larger than most butterflies with similar coloration. In contrast to the species that most closely resembles monarchs— viceroys—monarchs lack the black line crossing the middle of each hind wing. Behaviorally, monarchs tend to glide more than most other butterfly species. Life cycle: Western monarchs generally breed west of the Rocky Mountains and overwinter along the Pacific coast. However, there is some mixing between the western and eastern populations (which breed east of the Rocky Mountains and overwinter in central Mexico), with some western monarchs migrating to central Mexico. Monarchs have several generations a year, which spread out and move north and west from the overwintering sites. Adults and larvae can be found in the West throughout the breeding season. In the Great Basin, monarch breeding season typically occurs from May through October (Figure 3- 1). In the fall, adult monarchs enter reproductive diapause and return to overwintering sites along the California coast. Those individuals leave the overwintering grounds in spring to lay eggs on milkweeds, Monarch butterfly larvae  Photo Credit: Ray Moranz/The Xerces  Society 

Chapter 3. Imperiled Pollinator Profiles  3-4 the larval host plant. While larvae specialize on milkweed, adults use a variety of plants for nectar (Table 3-2). Habitat needs: Although monarchs tend to avoid dense forests, they use most terrestrial and wetland ecosystems for breeding and migration, as long as those ecosystems have milkweeds and nectar sources. This includes roadsides: monarchs lay eggs on a variety of milkweed species on roadsides and in roadside ditches. Top reasons for decline, if known: Loss and degradation of overwintering and breeding habitat; loss of habitat via conversion to row-crop agriculture and urban development; use of herbicides that kill milkweeds and nectar sources; use of insecticides that kill monarchs or cause negative but sublethal effects. General conservation recommendations: Protect and restore breeding habitat in the Great Basin; this includes planting of native milkweed and nectar plants. Reduced use of pesticides will benefit the conservation of this species. Roadside management recommendations: Mowing during the breeding season (May through October) will likely kill many monarch eggs, larvae, and pupae. Spraying of herbicides may kill milkweed and nectar plants. Table 3-2. Plants used by western monarchs. Species Name  Common Name  Larval Host Plants  Asclepias speciosa  Showy milkweed  Asclepias asperula  Spider milkweed  Asclepias erosa  Desert milkweed  Asclepias fascicularis  Narrow‐leaved milkweed  Asclepias subverticillata  Horsetail milkweed  Nectar Plants  Cleome lutea  Yellow spiderflower  Cleome serrulata  Rocky Mountain beeplant  Eriogonum umbellatum  Sulphur‐flower buckwheat  Heliotropium curassavicum  Salt heliotrope  Helianthus annuus  Common sunflower  Solidago canadensis  Canada goldenrod  Sphaeralcea ambigua  Desert globemallow 

Chapter 3. Imperiled Pollinator Profiles  3-5 Taken from handout created by Monarch Joint Venture and The Xerces Society:  https://monarchjointventure.org/images/uploads/documents/MowingForMonarchsUpdated.pdf.  Figure 3-1. Management timing windows for monarchs in the United States. Roadside milkweed guides:  Milkweeds of ID, OR and WA: https://xerces.org/publications/fact-sheets/roadside- habitat-for-monarchs-milkweeds-of-id-or-wa  Milkweeds of NV and UT: https://xerces.org/publications/fact-sheets/roadside- habitat-for-monarchs-milkweeds-of-nv-ut 3.1.1 References Dilts, T. E., M. O. Steele, J. D. Engler, E. M. Pelton, S. J. Jepsen, S. J. McKnight, A. R. Taylor, C. E. Fallon, S. H. Black, E. E. Cruz, D. R. Craver, and M. L. Forister. 2019. “Host Plants and Climate Structure Habitat Associations of the Western Monarch Butterfly.” Frontiers in Ecology and Evolution 7:188. Espeset, A. E., J. G. Harrison, A. M. Shapiro, C. C. Nice, J. H. Thorne, D. P. Waetjen, J. A. Fordyce, and M. L. Forister. 2016. “Understanding a migratory species in a changing world: climatic effects and demographic declines in the western monarch revealed by four decades of intensive monitoring.” Oecologia 181(3):819–830.

Chapter 3. Imperiled Pollinator Profiles  3-6 Pelton, E. M., C. B. Schultz, S. J. Jepsen, S. H. Black, and E. E. Crone. 2019. “Western Monarch Population Plummets: Status, Probable Causes, and Recommended Conservation Actions.” Frontiers in Ecology and Evolution 7:258. Satterfield, D. A., F. X. Villablanca, J. C. Maerz, and S. Altizer. 2016. “Migratory monarchs wintering in California experience low infection risk compared to monarchs breeding year-round on non-native milkweed.” Integrative and Comparative Biology 56(2):343– 352. Schultz, C. B., L. M. Brown, E. Pelton, and E. E. Crone. 2017. “Citizen science monitoring demonstrates dramatic declines of monarch butterflies in western North America.” Biological Conservation 214:343–346. The Xerces Society. 2018. Managing for monarchs in the west: best management practices for conserving the monarch butterfly and its habitat. The Xerces Society for Invertebrate Conservation, Portland, OR. Available: www.xerces.org. 3.2 Carson Wandering Skipper (Pseudocopaeodes eunus  obscurus)  Jan  Feb  Mar  April  May  June  July  Aug  Sept  Oct  Nov  Dec  Adult  Larvae  Adult Carson wandering skipper (top left) and known distribution (top right). Adult flight times (i.e.,  breeding period; blue) and larvae active periods (green) are shown in the chart (bottom). See Life Cycle for  more. Photo credit: Mace Vaughan. Map Source: ecos.fws.gov, accessed March 2022.  Order: Lepidoptera Family: Hesperiidae Status: Endangered Distribution: California, Nevada

3-7 Chapter 3. Imperiled Pollinator Profiles  Where it occurs: The species is found in grassland habitat with alkaline soils where saltgrass, the larval host plant, occurs. Populations of the Carson wandering skipper have been found in Carson Valley, Nevada; the Honey Lake Basin in California and Nevada; Spanish Springs Valley, Nevada; and Warm Springs Valley, Nevada. Adults of this species have also been found nectaring on flowers along roadsides. How to recognize: A small brownish-orange butterfly that can easily blend in with its pale saltgrass habitat. The upper side is a dullish orange-brown; other subspecies of P. eunus are a bright yellow-orange on top. The upper side also has black veins and a black terminal line along the wing edge. The underside is a dull, pale orange with a cream ray running from the wing base to the margin, and also has black veins. Adults hold their wings at 45- degree angles when perched. Life cycle: Adults are found during June and July, when they lay eggs on saltgrass. The larvae construct a nest at the base of saltgrass by rolling up leaves. They enter diapause and spend the winter and spring in these nests. The larvae finish feeding in early summer of the next year and pupate in May and June before emerging as adults. Adult life span probably lasts 1 to 2 weeks. Habitat needs: The Carson wandering skipper is a larval specialist, using saltgrass (Distichlis spicata var. stricta) as a host plant. Adults drink nectar from a variety of plants (Table 3-3). Key habitat features may include microtopography, with berms and saltgrass hillocks providing important variation in topography that may reduce the effects of flooding on diapausing larvae. This species appears to prefer sites lower than 5,000 feet in elevation. Top reasons for decline, if known: Habitat loss due to development; habitat fragmentation; habitat degradation caused by invasive species and changes in surface water (especially springs) and groundwater management. General conservation recommendations: Avoid disturbing existing saltgrass habitat near known or extirpated populations. Plant known nectar plants and host plants. Control the invasive plant tall whitetop (Lepidium latifolium) where it occurs along roadsides. Increased habitat connectivity (such as by providing roadside habitat) will combat effects of habitat fragmentation and help this species persist. Roadside management recommendations: Mowing saltgrass could kill diapausing larvae. If saltgrass is in roadside habitat, use a high mowing height (approximately 8 inches) to avoid diapausing larvae. Carson wandering skippers have also been found nectaring on flowers in roadside habitat. Summer mowing when adults are flying during June and July could reduce availability of nectar plants; leave patches of flowering plants when possible. Avoid spraying saltgrass or nectar plants with herbicides. Table 3-3. Plants used by the Carson wandering skipper. Species Name  Common Name  Larval Host Plants  Distichlis spicata var. stricta  Saltgrass1 

Chapter 3. Imperiled Pollinator Profiles  3-8 Species Name  Common Name  Nectar Plants  Thelypodium crispum  Crisped thelypody  Sisymbrium altissimum  Tall tumblemustard2  Pyrrocoma racemosa  Clustered goldenweed  Cirsium arvense  Canada thistle2  Cirsium vulgare  Common thistle, bull thistle2  Lotus tenuis  Narrow‐leaved bird's‐foot‐trefoil  Cleomella parviflora  Slender cleomella  Cleomella plocasperma  Twisted cleomella  Heliotropium curassavicum  Salt heliotrope  Potentilla sp.  Cinquefoils3  Sesuvium verrucosum  Western sea purslane  1 Does best when roots are inundated with water for a short time each spring  2 Nonnative species  3 This genus includes native and nonnative species; some of the nonnative species are invasive  3.2.1 References Sanford, M. P. 2006. “Conservation of the endangered Carson wandering skipper (Pseudocopaeodes eunus obscurus Austin and Emmel) in Western Great Basin saltgrass communities.” Natural Areas Journal 26:396–402. Available: https://www.fws.gov/nevada/protected_species/inverts/species/cws.html. 3.3 Bumble Bees: Yellow Bumble Bee (Bombus fervidus),  Morrison’s Bumble Bee (B. morrisoni), Western Bumble  Bee (B. occidentalis), Suckley’s Cuckoo Bumble Bee (B.  suckleyi)  Order: Hymenoptera Family: Apidae Habitat Needs: Availability of food and nesting resources are key features in determining the success of a bumble bee colony. It is critical to maintain a bloom of floral resources throughout the spring, summer, and fall to supply bumble bees with a diversity and abundance of pollen and nectar, food for adults and larvae. Bumble bees nest above, on, or under the ground, utilizing pre-existing insulated cavities such as rock piles, areas of

Chapter 3. Imperiled Pollinator Profiles  3-9 dense vegetation (e.g., bunch grasses), or old bird nests or mouse burrows. See Table 3-4 for a list of plants used by bumble bees. Top reasons for decline, if known: There are multiple factors affecting bumble bee decline including habitat loss, pesticide exposure, climate change, pathogens, and parasites, as well as the introduction of nonnative bee species. General conservation recommendations: Preserve, restore, and create high-quality habitat that includes suitable nesting, foraging, and overwintering sites throughout a species’ range. Assess and mitigate risk of pesticide use in or near suitable habitat to avoid treating flowers in bloom or contaminating nesting and overwintering sites. Avoid the introduction of managed honey bees and managed bumble bees to areas of natural habitat to protect and minimize disease exposure. Roadside management recommendations: Intensive mowing may deplete floral resources and potentially disturb species that have nested above ground in the roadside. Reduced mowing frequency would alleviate this problem. In areas with aboveground nesting species, avoid mowing during the nesting season to avoid harming nests. Use a diversity of plants in revegetation to ensure multiple species are in bloom from spring through fall. Blanket spraying of herbicides can affect the health of bumble bees in the area by reducing floral resources. A recent study of roadside mortality of bumble bee queens in Sweden found that bumble bee queens used roadsides with both high plant diversity and low plant diversity in similar proportions when looking for nests. Queen mortality increased with traffic volume but was slightly lower along roadsides with higher quality vegetation. The authors recommend improving habitat quality along roadsides, and keeping a mown buffer strip next to the road to reduce queen mortality. 3.3.1 Yellow Bumble Bee (Bombus fervidus) Jan  Feb  Mar  April  May  June  July  Aug  Sept  Oct  Nov  Dec  Adult  Adult yellow bumble bee (top left) and known U.S. state‐level distribution (top right). Adult flight times  (i.e., breeding period) are shown in the chart (bottom). Photo credit: Katie Lamke/The Xerces Society.   

Chapter 3. Imperiled Pollinator Profiles  3-10 Status: Vulnerable to apparently secure (G3G4) Distribution: Widespread across the United States, except for states in the south-central and southeastern states. Where it occurs: Grassland, urban, forest, shrubland Flight Time: This species is typically active on the landscape from May through September. Between late October and April, queens are overwintering in the ground. Nesting behavior: Nests on the surface or aboveground; occasionally nests underground. How to recognize: This bumble bee has black hair on the face; a yellow thorax with a narrow, black band between the wings; and a predominantly yellow abdomen with a black posterior end. Males may have different color patterns. Body size: Medium. Queens range from 18 to 21 millimeters (0.72 to 0.84 inch) and workers range from 11 to 17 millimeters (0.42 to 0.67 inch). 3.3.2 Morrison’s Bumble Bee (Bombus morrisoni) Jan  Feb  Mar  April  May  June  July  Aug  Sept  Oct  Nov  Dec  Adult  Adult Morrison’s bumble bee (top left) and known U.S. state‐level distribution (top right). Adult flight times  (i.e., breeding period) are shown in the chart (bottom). Photo credit: Leif Richardson/The Xerces Society.   

Chapter 3. Imperiled Pollinator Profiles  3-11 Status: Vulnerable (G3) Distribution: Mountain and desert West Where it occurs: Dry shrubland Flight Times: This species is typically active on the landscape from early May through mid-October. Between November and April, queens are overwintering in the ground. Nesting behavior: Nests underground. How to recognize: This bumble bee has black hair on the front of the face and yellow hair on the top of the head. The thorax is predominantly yellow, and black on the side. On the abdomen, segments one and two are yellow, segment three has some yellow, and segments four to six are black. Males may have different color patterns. Body size: Large. Queens range from 22 to 26 millimeters (0.87 to 1.02 inches) and workers range from 12 to 22 millimeters (0.47 to 0.87 inch). 3.3.3 Western Bumble Bee (Bombus occidentalis) Jan  Feb  Mar  April  May  June  July  Aug  Sept  Oct  Nov  Dec  Adult  Larvae  Adult western bumble bee (top left) and known U.S. state‐level distribution (top right). Adult flight times  (i.e., breeding period) are shown in the chart (bottom). Photo credit: Rich Hatfield.    Status: Vulnerable (G3), under review; petitioned in 2018 to be listed as endangered under the California Endangered Species Act; petitioned in 2015 to be listed as endangered or threatened under the ESA Distribution: Western United States from the coast to mountain meadows out to the northwestern Great Plains. Population has shown sharp decline since the late 1990s west of the Sierra-Cascade ranges. Where it occurs: Urban, shrubland, grassland

Chapter 3. Imperiled Pollinator Profiles  3-12 Flight Time: This species is typically active on the landscape from May through September. Between October and April, queens are overwintering in the ground. Nesting behavior: Usually nests underground. How to recognize: This bumble bee has mixed black and yellow hair on the face. The thorax has a yellow band in front of the wings and a black band or spot between the wings; behind the wings can be black, yellow, or mixed. Segment one of the abdomen is black, segments two and three are black or have some yellow, segments four and five are white or pale yellow, and segment six is black. Males may have different color patterns. Body size: Medium. Queens range from 20 to 21 millimeters (0.77 to 0.84 inch) and workers range from 9 to 15 millimeters (0.36 to 0.59 inch). 3.3.4 Suckley’s Cuckoo Bumble Bee (Bombus suckleyi)   Jan  Feb  Mar  April  May  June  July  Aug  Sept  Oct  Nov  Dec  Adult                                                                                                Adult Suckley’s cuckoo bumble bee (top left) and known U.S. state‐level distribution (top right). Adult flight  times (i.e., breeding period) are shown in the chart (bottom). Photo credit: Cory Sheffield.    Status: Imperiled to vulnerable (G2G3); under review for listing under the ESA Distribution: Mountain west and north into Canada Where it occurs: Forest, grassland, shrubland Parasite of: Western bumble bee (B. occidentalis) Flight Times: This species is typically active on the landscape in June and again in early to mid-August. During the peak of summer, this species remains in the host’s nest. Nesting behavior: Parasite of western bumble bee, which nests underground. How to recognize: This bumble bee has black hair on the face and a predominantly yellow thorax with a black stripe between the wings. The abdomen is predominantly black with a yellow band toward the posterior end interrupted medially. Males may have different color patterns.

3-13 Chapter 3. Imperiled Pollinator Profiles  Body size: Medium. Females range from 18 to 23 millimeters (0.72 to 0.92 inch). Table 3-4. Plants used by bumble bees. Species name by bloom period  Common name  Notes   Early  Asclepias asperula  Spider milkweed  White/green; perennial  Cirsium neomexicanum  New Mexico thistle  White/pink/purple; biennial  Eschscholzia californica  California poppy  Orange; annual or perennial  Phacelia tanacetifolia  Lacy phacelia  Blue/purple; annual  Mid  Astragalus canadensis  Canada milkvetch  White; perennial  Hedysarum boreale  Utah sweetvetch  Pink; perennial  Lupinus argenteus  Silvery lupine  White/purple; perennial  Prunella vulgaris ssp. lanceolata  Lance selfheal  Purple; perennial  Late  Asclepias speciosa  Showy milkweed  Pink; perennial  Eriophyllum lanatum  Common woolly sunflower  Yellow; annual or perennial  Solidago canadensis  Canada goldenrod  Yellow; perennial  Symphyotrichum laeve  Smooth blue aster  Purple/blue; perennial  3.3.5 References Dániel-Ferreira, J., Å. Berggren, R. Bommarco, J. Wissman, and E. Öckinger. 2022. Bumblebee queen mortality along roads increase with traffic. Biological conservation 272:109643. Hatfield, R., S. Jepsen, E. Mader, S. H. Black, and M. Shepherd. 2012. Conserving bumble bees. Guidelines for Creating and Managing Habitat for America's Declining Pollinators. The Xerces Society for Invertebrate Conservation, Portland, OR. Williams, P. H., R. W. Thorp, L. L. Richardson, and S. R. Colla. 2014. Bumble Bees of North America: An Identification Guide. Princeton University Press, Princeton, NJ. doi:10.2307/j.ctt6wpzr9.

Chapter 3. Imperiled Pollinator Profiles  3-14 3.4 Desert Green Hairstreak (Callophrys sheridanii ssp.)    Jan  Feb  Mar  April  May  June  July  Aug  Sept  Oct  Nov  Dec  Adult                                                                                                Larvae                                                                                                Adult desert green hairstreak (top left) and known state‐level distribution (top right). Adult flight times  (i.e., breeding period; blue) and larvae active periods (green) are shown in the chart (bottom). In some  years, this species has partial flights in June/July or August/September (see Life Cycle for more). Lighter  shades indicate uncertain but likely active times. Photo credit: Ken Kertell.    Order: Lepidoptera Family: Lycaenidae Status: Secure; taxon vulnerable to apparently secure (G5T3T4) Distribution: Arizona, California, Colorado, Nevada, Utah Where it occurs: This species is found in remote desert canyons of the Great Basin and arid intermountain West. The subspecies C. s. interrupta is endemic to northern Nevada, while C. s. comstocki is found in the Mojave Desert of southern Nevada, southeastern California, western Arizona, and southwestern Utah. How to recognize: This small hairstreak butterfly is gray from above and bright green to gray-green from below, with a row of small white dots edged in black present on each hindwing). In C. s. interrupta, this line may be present or mostly absent; in C. s. comstocki, this line is almost always continuous across the entire hind wing. Life cycle: In the Great Basin, adults are active from April through June, while in the Mojave adults fly from March to early May and in some years may have additional partial flights in June/July and/or August/September, usually dependent on elevation. Males perch and wait for females in gulch bottoms and females lay eggs singly on buckwheat hostplants. This species overwinters in the pupal stage in litter at the base of the plant. Habitat needs: The desert green hairstreak is found in sagebrush scrub and pinyon- juniper woodlands of the Great Basin. Larvae depend on various species of buckwheat (Eriogonum), while adults feed on flower nectar from a variety of species).

3-15 Chapter 3. Imperiled Pollinator Profiles  Top reasons for decline, if known: Degradation of habitat by invasive vegetation, particularly cheatgrass (Bromus tectorum), and the increased frequency and intensity of wildfires associated with it. General conservation recommendations: Manage the spread of invasive plants like cheatgrass to the extent possible, and mitigate the impacts of fire on this species. Roadside management recommendations: The subspecies C. s. interrupta has historically been found along roadsides in multiple locations in central Nevada. Development or roadside maintenance that results in the spread of invasive plants or the eradication of native buckwheat host plants could be detrimental to this species. Reduce mowing frequency beyond the clear zone. When possible, time mowing in areas with this species to late fall through early spring when the butterflies are in the pupal stage. Because they pupate in litter at the base of host plants, this will reduce mortality effects of mowing. Table 3-5. Plants used by the desert green hairstreak. Species Name  Common Name  Larval Host Plants  Eriogonum heermannii  Heermann’s buckwheat1  Eriogonum racemosum  Redroot buckwheat  Eriogonum umbellatum  Sulphur‐flower buckwheat  Eriogonum wrightii  Bastardsage  Nectar Plants  Arctostaphylos uva‐ursi  kinnikinnick  Cerastium arvense strictum  Field chickweed  Claytonia rosea  Western springbeauty  Eriogonum umbellatum  Sulphur‐flower buckwheat  Mahonia repens  Creeping barberry  Noccaea fendleri  Fendler’s pennycress  Salix spp.  Willow   Thlaspi arvense  Field pennycress2 1 Suspected host plant in California  2 Nonnative 

Chapter 3. Imperiled Pollinator Profiles  3-16 3.4.1 References Austin, G. T. 1998. Callophrys (Lepidoptera: Lycaenidae) in Nevada, with description of a new subspecies of C. comstocki. In: Emmel, T.C. ed. Systematics of western North American butterflies. The Mariposa Press, Gainesville, FL. Austin, G. T., and P. J. Leary. 2008. “Larval host plants of butterflies in Nevada.” Holarctic Lepidoptera 12(1-2):1–150. Lotts, K., and T. Naberhaus, coordinators. 2017. Butterflies and moths of North America. Available: www.butterfliesandmoths.org (Version 09292020). NatureServe. 2020. NatureServe Explorer (web application). NatureServe, Arlington, Virginia. Available: https://explorer.natureserve.org/. Accessed: September 29, 2020. Opler, P. A., and A. B. Wright. 1999. A Field Guide to Western Butterflies. Second edition. Peterson Field Guides. Houghton Mifflin Company, Boston, MA. Scott, J. A. 1986. The Butterflies of North America: A Natural History and Field Guide. Stanford University Press, Stanford, CA. Scott, J. A. 2014. Lepidoptera of North America. 13. Flower visitation by Colorado butterflies (40,615 records) with a review of the literature on pollination of Colorado plants and butterfly attraction (Lepidoptera: Hesperioidea and Papilionoidea). Contributions of the C.P. Gillette Museum of Arthropod Diversity, Colorado State University. Vaughan, D. M., and M. D. Shepherd. 2005. Species Profile: Callophrys comstocki. In Shepherd, M. D., D. M. Vaughan, and S. H. Black (Eds). Red List of Pollinator Insects of North America. CD-ROM Version 1 (May 2005). Portland, OR: The Xerces Society for Invertebrate Conservation