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Species Hyalophora euryalus - Ceanothus Silkmoth - Hodges#7770

Hyalophora kasloensis 01 - Hyalophora euryalus - female Hyalophora euryalus (nr. Hyalophora Hyalophora Hyalophora euryalus? - Hyalophora euryalus Hylaphora euryalus? - Hyalophora euryalus Moth - Hyalophora euryalus - female Hyalophora euryalus kasloensis Cocoon - Hyalophora euryalus
Show images of: caterpillars · adults · both
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Bombycoidea (Silkworm, Sphinx, and Royal Moths)
Family Saturniidae (Giant Silkworm and Royal Moths)
Subfamily Saturniinae (Silkmoths)
Tribe Attacini
Genus Hyalophora
Species euryalus (Ceanothus Silkmoth - Hodges#7770)
Hodges Number
Synonyms and other taxonomic changes
Samia rubra

Hyalophora "kasloensis" (recently ranked as a subspecies under euryalus)
Explanation of Names
EURYALUS: from the Greek "eurys" (broad) + the Latin "ala" (wing)
Wingspan 89-127 mm
Adult: overall similarity to Columbia Silkmoth and Cecropia Moth except area beyond PM line maroon, purple, or pinkish, in a broad diffuse band; discal spot on hindwing shaped like an elongated comma pointing toward outer margin, sometimes breaking PM line.

This species is highly variable in color and pattern across its range (esp. when you factor in all three "subspecies" and seasonal/geographic color variants). Typically as described above; however, the discal spot (i.e. the elongated comma-shaped pattern often described as a "Nike Swoosh") may be reduced or even absent in extreme cases. Some individuals may be dark chocolate brown in appearance with strong grey suffusion submarginally (not typical, yet characteristic of more northern populations).


Larva: changes colors as it develops and molts; mid instars are the most brilliantly colored with nine pairs of dorsal yellow spines, the first three pairs with partial to complete black rings; a middorsal yellow spine on A8; two rows of lateral blue spines tipped with white along T1-A8; white-tipped blue spines also occur on the head, at the base of the true legs, and in the anal region; body ranges from green to whitish-green
later instars whitish-green with white spines
[adapted from description by Jeffrey Miller]
British Columbia to western Montana, south through west coast states to Baja California.
In California, found mostly west of the Sierras.

w. Mexico (ssp. euryalus along Pacific coastal areas & ssp. cedrosensis on Cedros Island)
w. USA (Pacific coast mostly west of the Sierras and Cascades - ssp. kasloensis in Cascades extending east in w. MT)
w. Canada (ssp. euryalus along coast and ssp. kasloensis inland)
coastal areas, chaparral, intermontane valleys, conifer forests
adults fly from January to July, depending on altitude, latitude, and seasonal variation
larvae in July and August
Larvae feed on a number of trees and shrubs, including Red Alder (Alnus rubra), birch, Antelope Bitterbrush (Purshia tridentata), buckthorn (Rhamnus), Buffaloberry (Sheperdia canadensis), Ceanothus species, cherry, gooseberry (Ribes), Hardhack (Spiraea douglasii), hazel, Madrone (Arbutus menziesii), manzanita (Arctostaphylos), Mountain Mahogany (Cercocarpus betuloides), Mountain Maple (Acer glabrum), rose, Saskatoon Serviceberry (Amelanchier alnifolia), willow (Salix), and occasionally Douglas-fir (Pseudotsuga menziesii).
Life Cycle
eggs laid singly or in clumps on leaves of host plant, hatching in 9-14 days; overwinters as a pupa in teardrop-shaped cocoon attached to twig on outer part of host plant.

Most populations are "univoltine" with rare incidental eclosions. Most records place adults between the months of March-July (supplemental reports incl. January-August).

In western coastal Mexico, adults of Hyalophora euryalus may be encountered all months of the year and often based on precipitation patterns; however, there is debate regarding number of generations. There is also debate regarding misidentifications of related taxa (Rothschildia and allied atttacini saturniids).
The range of Hyalophora euryalus overlaps with H. "kasloensis", H. columbia (and its subspecies H. c. gloveri); hybridization often occurs where the various taxa meet.

Currently, there are three recognized "subspecies" as follows:

Pacific coast west of the Cascades and Sierras (incl. sw. BC, Canada; Pacific coast of the USA; ranging south into Baja Mexico/Pacific coast of c. Mex.)

RARE ENDEMIC of La Isla de Cedros, Baja Calif., Mexico

A distinct "population group" of hybrid origin (euryalus X columbia group) with strong ties to the euryalus complex and currently recognized as a "subspecies" of euryalus. Isolated to a region east of the Cascades and west of the Rockies (incl. e. Washington, n. Idaho & w. Montana in the USA & sc. B.C. in Canada)
See Also
The Columbia Silkmoth, Hyalophora columbia ssp. columbia and Glover's Silkmoth, Hyalophora columbia ssp. gloveri with rare exception (incl. Blend zones, Mexican/Sonoran variants), LACK maroon or purplish shading beyond PM line of wings, and the hindwing discal spots are not as elongated.

NOTE: Hyalophora gloveri ("Sonoran & Mexican variants") may be similar in color & pattern to euryalus and kasloensis.

*Compare additional images of euryalus & gloveri.
Observation: Regarding this link, 1st image identified as "euryalus" in this series (2nd to last pic) is suspect (Noting the presence of a red postmedial line as seen in cecropia & cecropia blends). All pattern forms, color forms and geographic variations of "euryalus" considered, this particular specimen is inconsistent with "euryalus" and is more typical of a "cecropia blend" in characteristics. No additional collection/rearing data regarding location/origin for this specimen was available (??).

Cecropia Moth, Hyalophora cecropia, has more gray in the basal half of the wings, the reddish band beyond the PM line is narrow and sharply defined (not broad and diffuse), and the discal spots on its hindwing are not elongated.

*(Additional images of H. euryalus). NOTE: 1st image identified as euryalus is suspect (appears to have strong cecropia traits, i.e. red postmedial line - possible lab cross??)

List of similar taxa:

Print References
Miller and Hammond, #235, p. 108 (1)
Tuskes et al., pp. 211-213, plates 28--adult, 6--larva, fig. 43--cocoon (2)
Powell and Hogue, p. 228, plate 11d--adult, 11e--larva (3)
Internet References

Butterflies and Moths of North America - adult and larva images, description, flight season, food plants, biology, habitat, references, US distribution map (Opler, Paul A., Harry Pavulaan, Ray E. Stanford, Michael Pogue, contributors)
Caterpillars of Pacific Northwest Forests and Woodlands - live larva image, description, food plants, seasonality (Jeffrey Miller; USGS)
live images of all life stages plus description and comments (Jeremy Tatum, Butterflies and Moths of Southern Vancouver Island)
live images of all life stages (Peter Bryant, Moths of Orange County, U. of California at Irvine)
live adult image plus description, food plants, biology, distribution (G.G. Anweiler, U. of Alberta)
food plants plus synonyms, links, references (Markku Savela, FUNET)
Works Cited
1.Macromoths of Northwest Forests and Woodlands
Jeffrey Miller, Paul Hammond. 2000. USDA Forest Service, FHTET-98-18.
2.The Wild Silk Moths of North America: A Natural History of the Saturniidae of the United States and Canada
Paul M. Tuskes, James P. Tuttle, Michael M. Collins. 1996. Cornell University Press.
3.California Insects
Jerry A. Powell, Charles L. Hogue. 1989. University of California Press.