Skippers: Huachuca giant-skipper (Agathymus evansi)

(Lepidoptera: Hesperiidae: Megathyminae: Aegialini)

Profile prepared by Mace Vaughan and Matthew Shepherd, The Xerces Society for Invertebrate Conservation

The Huachuca giant-skipper is restricted to mix woodland s above 1,800 meters in the Huachuca Mountains of southern Arizona and similar isolated “sky islands” in the Sonoran Desert of Mexico. Its larval hostplant is Parry’s agave, although the skipper does not occur everywhere the agave grows. This butterfly has very few populations and is threatened by overgrazing and wildfire.

red list profile

conservation status

Xerces Red List Status: 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: None
NatureServe: G2G3
IUCN Red List: N/A

This skipper is considered imperiled. There are fewer than twenty known metapopulations in its entire range. It is not protected under any legislation at either federal or state level in either country.

description and taxonomic status

The Huachuca giant-skipper is in the family Hesperiidae. As its common name suggests, this is a large skipper, with a wingspan of 45mm to 61 mm (1¾ to 2⅜ inches).

The upperside of the wings are very dark black-brown with orange at the wing bases. On each wing is a narrow band of spots separated by black veins. The spots are yellow on the males and yellow-orange on females. The underside of the hindwing is mottled gray and brown with pale overscales, and has an indistinct pale band.

Taxonomic status

Agathymus evansi (H. A. Freeman), 1950. This species was previously placed in the genus Megathymus. The genus Agathymus is a group of very similar species. It has been suggested that evansi is a subspecies but it is accepted as a full species by all recent authors. Other common names include Brigadier, Evans’ Giant-skipper, and Evan’s Agave Borer.

life history

The habitat for these butterflies is mixed pine-oak-juniper woodland containing the larval hostplant, Parry’s agave (Agave parryi). The butterflies are generally found at altitudes 1,800 m.

Eggs are laid singly by scattering them on the agave; they then fall to the ground. Once hatched, the caterpillar crawls back up the plant to a leaf tip and burrows inside. The caterpillar both eats the pulp and hibernates inside the leaf. In spring, the caterpillar moves to a leaf base where it also burrows inside but now feeds on sap. The summer is spent in an inactive state (aestivation) before pupating. In preparation for pupation, the caterpillar widens the burrow entrance and covers it with silk through which the adult can emerge.

There is a single adult flight period. Most adults are active in September and October, although they have been recorded between early August and the beginning of November. The adults do not feed, but males will take moisture from mud. Males will spend the mornings perched on agave waiting for females.

distribution

The Huachuca giant-skipper is restricted to the Huachuca and Chiricahua Mountains, two of the “sky islands” in the Arizona Sonora Desert in southeastern Arizona, and similar mountain ranges in adjacent areas of Mexico’s Sonora Desert.


Courtesy of Butterflies and Moths of North America, Big Sky Institute.

threats and conservation needs

The Huachuca giant-skipper habitat is on mountains isolated from other similar areas by desert flats. Within these mountains the populations are at risk from livestock grazing and catastrophic wild fires.

The woodland habitat should be conserved wherever it occurs with Parry’s agave. This is especially important where the skipper occurs. These areas must be protected from overgrazing.

Monitoring and surveys are needed to confirm the range of the species and identify additional populations. The impact of grazing should be studied.

references

Bailowitz, R. A., and J. P. Brock. 1991. Butterflies of Southeastern Arizona. Sonoran Arthropod Studies, Inc., Tucson, AZ.

Opler, P. A. 1999. Peterson Field Guide to Western Butterflies, revised edition. Houghton Mifflin Co., Boston, MA.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, CA.

Stanford, R. E., and P. A. Opler. 1993. Atlas of Western USA Butterflies Including Adjacent Parts of Canada and Mexico. Denver and Fort Collins, CO.

Tilden, J. W. 1986. A Field Guide to Western Butterflies. Houghton-Mifflin Co., Boston, MA.

additional resources

Big Sky Institute, Butterflies and Moths of North America: Huachuca giant-skipper (Accessed 1/21/09)

Arizona Game and Fish Department; Invertebrate Abstract: Agathymus evansi (Accessed 5/4/05)

Nearctica; The Butterflies and Skippers of North America: Huachuca giant-skipper (Accessed 5/4/05)

NatureServe Explorer (Accessed 9/23/08)

National Wildlife Federation, eNature; Field Guides: Huachuca giant-skipper (Accessed 9/23/08)

citation

Vaughan, D. M., and M. D. Shepherd. 2005. Species Profile: Agathymus evansi. 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.

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