North American Butterflies and Moths List

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Butterflies of North America

Butterflies of California

Yucca Giant-Skipper (Megathymus yuccae (incl. coloradensis))
JPG -- species photo

Yucca Giant-Skipper (Megathymus yuccae [Boisduval & LeConte])

Wing span: 1 7/8 - 3 1/8 inches (4.8 - 7.9 cm).

Identification: Very large and robust. Forewing is long and pointed. Upperside is black; forewing with a yellow band near the lower outer margin and small white spots near the tip and costa; hindwing with a yellow band on the outer margin. Females may have orange-yellow to yellow spots on the hindwing. Underside of hindwing is gray with white spots on the costa.

Life history: Adults are very swift fliers. Males perch in the morning near the host plants to await females. Females glue eggs singly to leaves of small host plants. Young caterpillars feed near the tips of leaves and may web together small leaves to make a nest. Older caterpillars bore into the growing point of the plant and feed on the root, making a silk chimney or tent which projects from the growing point. Fully-grown caterpillars overwinter in their burrows and then pupate there in late winter or early spring. The chrysalids are able to move up and down in their burrows.

Flight: One brood from mid-February to mid-May.

Caterpillar hosts: Various yuccas including bear grass (Yucca filamentosa), Small's yucca (Y. smalliana), Spanish dagger (Y. gloriosa), (Y. elata), and (Y. arizonica) and Spanish bayonet (Y. aloifolia).

Adult food: Adults do not feed, but males take moisture at mud.

Habitat: Coastal dunes, open yucca flats, desert canyons, open woodland, grassland, and old fields.

Range: Western population: Southern California and central Nevada east to Nebraska and east Texas, south to northern Mexico. Southeastern population: Southeast Virginia south to southern peninsular Florida, west to Arkansas and Louisiana.

Conservation: Not usually required.

The Nature Conservancy Global Rank: G4 - Apparently secure globally, though it might be quite rare in parts of its range, especially at the periphery.

Management needs: None reported.


Bailowitz, R. A., and J. P. Brock. 1991. Butterflies of southeastern Arizona. 

     Sonoran Arthropod Studies, Inc., Tucson, Arizona. 342 pages.

Opler, P. A. and G. O. Krizek. 1984. Butterflies east of the Great Plains. Johns 

     Hopkins University Press, Baltimore. 294 pages, 54 color plates.

Opler, P. A. and V. Malikul. 1992. A field guide to eastern butterflies. Peterson 

     field guide #4. Houghton-Mifflin Co., Boston. 396 pages, 48 color plates.

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

     Stanford, Calif. 583 pages, 64 color plates.

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, Mass. 370 pages, 23 color plates.

Author: Jane M. Struttmann

State and Regional References:

Brown, J.W., Real, H.G., and D.K. Faulkner. 1992. Butterflies of Baja 

     California. Lepidoptera Research Foundation, Beverly Hills, Calif.

Comstock, J.A. 1927. Butterflies of California. Privately published, Los 

     Angeles, Calif. [Facsimile available from 	Entomological Reprint 

     Specialists, Los Angeles, Calif.]

Dameron, W. 1997. Searching for butterflies in southern California.

     Flutterby Press, Los Angeles, Calif.

Emmel, T.C. Editor. 1998. Systematics of western North American butterflies.

     Mariposa Press, Gainesville, Florida.

Emmel, T. C. and J. F. Emmel. 1973. The Butterflies of Southern California. 

     Natural History Museum of Los Angeles County Science Series No. 26.

Garth, J.S. and J.W. Tilden. 1986. California Butterflies.  California Natural

     History Guide 51. University of California Press, Berkeley and Los 



Langston, R.L. 1981. The Rhopalocera of Santa Cruz Island, California. Journal

     of Research on the Lepidoptera 18: 24-35.     

Miller, Scott E. 1985. Butterflies of the Califorenia Channel Islands. Journal

     of the Research on the Lepidoptera 23: 282-296.     

Opler, Paul A. 1999. Peterson Field Guide to Western Butterflies, revised 

     edition. Houghton Mifflin Co., Boston, Mass.

Orsak, L.J. 1977. The Butterflies of Orange County, California. Museum of 

     Systematic Biology, University of california, Irvine.

Stanford, R.E. and P.A. Opler. 1993. Atlas of Western USA Butterflies. 

     Privately published, Denver, Colo.

Steiner, J. 1990. Bay Area Butterflies: The Distribution and Natural History 

     of San Francisco Region Rhopalocera. Hayward, Calif.: Hayward State 

     University, Masters Thesis.

Tilden, J.W. and A.C. Smith. 1986. A Field Guide to Western Butterflies. 

     Houghton Mifflin Co., Boston, Mass.

Tilden, J.W. 1965. Butterflies of the San Francisco Bay Region. California 

     Natural History Guide 12. University of California Press, Berkeley and 

     Los Angeles.

Yucca Giant-Skipper (Megathymus yuccae (incl. coloradensis))
distribution map
map legend

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