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Lower Colorado River Multi-Species Conservation Program Balancing Resource Use and Conservation
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MacNeill's Sootywing

      (Pholisora gracielae=Hesperopsis gracielae)

MacNeill's Sootywing Late-instar larvaMacNeill's SootywingMacNeill's Sootywing Eggs

General Description

MacNeill’s sootywing skipper (Pholisora gracielae=Hesperopsis gracielae) is a small (0.75 to 1.25 inches, 20 to 32 mm) skipper with dark-brown and black mottled wings. Skippers are butterflies with widely-spaced antennae that are usually hooked.

Legal Status

MacNeill’s sootywing was previously a Federal category 2 candidate and is currently listed as a species of concern. The state ranking of this species in both California and Nevada is critically imperiled. In Arizona, the state ranking of this skipper is listed as imperiled and uncommon.


MacNeill’s sootywings (Pholisora gracielae=Hesperopsis gracielae (MacNeill)) was described in 1970. Scott (1986) considered it a subspecies of H. alpheus (W. H. Edwards), but this is not generally accepted. Common names include MacNeill’s saltbush sootywing and MacNeill’s sootywing.


MacNeill’s sootywings deposit white or red spherical eggs singly on quailbush leaves. Larvae undergo several molts before pupating, and larger larvae enclose themselves within leaf-folds of quailbush secured with silk produced near the mouth. The insect pupates within the wrapped leaf. Several adult flights occur per year.


Larvae feed only on quailbush. Adults require nectar obtained from flowers on a variety of plants including heliotrope and they also have been observed nectaring on quailbush.


The species was originally listed as Federal category 2 candidate due to conversion of riparian habitat to agriculture. MacNeill’s sootywing is susceptible to human disturbance from activities such as recreation, development, livestock grazing, and use of pesticides. The historical cause of species decline likely was agricultural development and drying of habitat due to river channelization and lowered water tables.

More Information

Additional information on this species, as well as source documentation, can be found in the species accounts located at this link (PDF). The Conceptual Ecological Model (CEM) can be found here (PDF), and the latest update can be found here. Technical Reports on this species can be found here.

Updated January 7, 2020

The historical range of MacNeill’s sootywing was along the lower Colorado River and its tributaries in southeastern California, western Arizona, southern Nevada, and southern Utah. The species was first identified along the California side of the lower Colorado River below Parker Dam near Parker, Arizona. The current range of MacNeill’s sootywing approximates the historical range, except its presence in southern Utah is uncertain.

MacNeill’s sootywing requires stands of quailbush (Atriplex lentiformis) near nectar-producing plants, such as heliotrope. The species is often found on quailbush with high leaf water content resulting from shallow groundwater or irrigation runoff. Habitat for MacNeill’s sootywing is desert washes, alkali flats, and arid canyons, particularly if they support scrub or chaparral vegetation.

LCR MSCP Conservation Measures

The Habitat Conservation Plan provides conservation measures specific to each species. Listed below are the species specific conservation measures for the MacNeill's sootywing. Click on the arrows to expand the table.

MNSW1—Conduct surveys and research to locate MacNeill's sootywing skipper habitat and to better define its habitat requirements

Conduct research to locate MacNeill's sootywing skipper populations that could be affected by covered activities and determine the macrohabitat and microhabitat requirements and ecology of the species. Based on research results, implement adaptive management experiments to develop habitat establishment and management methods.

MNSW2—Create at least 222 acres of MacNeill's sootywing skipper habitat

Based on results of research conducted under conservation measure MNSW1, at least 222 acres of MacNeill's sootywing skipper habitat will be created in Reaches 1–4 near occupied habitat. Patches of created habitat will be designed and managed to support a mix of honey mesquite type III and quailbush to provide food plants for caterpillars and adults and to maintain the microhabitat conditions required by the species. A substantial amount of the 1,320 acres of honey mesquite type III that would be created is expected to be created in reaches occupied by this species and will be established in conjunction with quailbush, the species' larval host plant. Consequently, it is anticipated substantially more than 222 acres of habitat could be created under the LCR MSCP.

MRM2—Monitor and adaptively manage created covered and evaluation species habitats

Created species habitats will be managed to maintain their functions as species habitat over the term of the LCR MSCP. Created habitat will be monitored and adaptively managed over time to determine the types and frequency of management activities that may be required to maintain created cottonwood-willow, honey mesquite, marsh, and backwater land cover as habitat for covered species. This conservation measure applies to those species for which comparable measures are not subsumed under species-specific conservation measures (Section 5.7 in the HCP). They are not applicable to species for which habitat would not be created under the LCR MSCP Conservation Plan, such as the desert tortoise, relict leopard frog, humpback chub, and threecorner milkvetch.

CMM1—Reduce risk of loss of created habitat to wildfire

Management of LCR MSCP conservation areas will include contributing to and integrating with local, state, and Federal agency fire management plans. Conservation areas will be designed to contain wildfire and facilitate rapid response to suppress fires (e.g., fire management plans will be an element of each conservation area management plan).

CMM2—Replace created habitat affected by wildfire

In the event of created-habitat degradation or loss as a result of wildfire, land management and habitat creation measures to support the reestablishment of native vegetation will be identified and implemented.

AMM1—To the extent practicable, avoid and minimize impacts of implementing the LCR MSCP on existing covered species habitats

To the extent practicable, establishment and management of LCR MSCP–created habitats will avoid removal of existing cottonwood-willow stands, honey mesquite bosques, marsh, and backwaters to avoid and minimize impacts on habitat they provide for covered species. Temporary disturbance of covered species habitats, however, may be associated with habitat creation and subsequent maintenance activities (e.g., controlled burning in marshes and removal of trees to maintain succession objectives). LCR MSCP conservation measures that could result in such temporary disturbances will, to the extent practicable, be designed and implemented to avoid or minimize the potential for disturbance. In addition to implementing AMM3 and AMM4 below, these measures could include conducting preconstruction surveys to determine if covered species are present and, if present, implementing habitat establishment and management activities during periods when the species would be least sensitive to those activities; or redesigning the activities to avoid the need to disturb sensitive habitat use areas; staging construction activities away from sensitive habitat use areas; and implementing BMPs to control erosion when implementing ground disturbing activities.

AMM5—Avoid impacts of operation, maintenance, and replacement of hydroelectric generation and transmission facilities on covered species in the LCR MSCP planning area

To the extent practicable, before implementing activities associated with OM&R of hydroelectric generation and transmission facilities, measures will be identified and implemented that are necessary to avoid take of covered species where such activities could otherwise result in take. These measures could include conducting surveys to determine if covered species are present and, if so, deferring the implementation of activities to avoid disturbance during the breeding season; redesigning the activities to avoid the need to disturb covered species habitat use areas; staging of equipment outside of covered species habitats; delineating the limits of vegetation control activities to ensure that only the vegetation that needs to be removed to maintain infrastructure is removed; stockpiling and disposing of removed vegetation in a manner that minimizes the risk of fire; and implementing BMPs to control erosion when implementing ground disturbing activities.

Research and Monitoring Activities

LCR MSCP conducts a variety of research and monitoring activities along the LCR encompassing both MSCP and non-MSCP species. For a complete list of all activities, please see the Research and Monitoring Activities web page.

This gallery includes photos of this species. If you require larger photos, please contact our webmaster Michelle Reilly at mreilly@usbr.gov.

Adult MacNeill's sootywing feeding at a heliotrope inflorescence in 2006 at Cibola National Wildlife Refuge, near Blythe, CA - Photo by Reclamation Eggs of MacNeill's sootywing on an Atriplex lentiformis leaf near the Muddy River in southern Nevada in 1999 - Photo by Reclamation Late-instar larva of MacNeill's sootywing within a rolled Atriplex lentiformis leaf near the Muddy River in 1999 - Photo by Reclamation Rolled Atriplex lentiformis leaf containing a MacNeill's-sootywing larva near the Muddy River in 1999 - Photo by Reclamation Early-instar larva of MacNeill's sootywing feeding on an Atriplex lentiformis leaf near the Muddy River in 1999 - Photo by Reclamation MacNeill's Sootywing - Photo by Reclamation MacNeill's Sootywing larvae in hand - Photo by Reclamation