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Genus Hyalophora

Ceanothus Silk Moth - Hyalophora euryalus - female Hyalophora Hyalophora cecropia - male Cecropia Moth H#7767 - Hyalophora cecropia Cecropia moth - Hyalophora cecropia Cercropia Moth - Hyalophora cecropia Eagle Butte Trail Caterpillar - Hyalophora cecropia Large Moth Cacoon - Hyalophora cecropia
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
Synonyms and other taxonomic changes
(Members of this group are often listed under Samia &/or Platysamia in older lit.)
Explanation of Names
Hyalophora is apparently from Greek Hyalos (υαλος)- "glass" and phoros (φορος)- "bearing, carrying"
Variable, ranging from 3 to 6 inch wing spans (Typically - with Hyalophora columbia ssp. columbia nominate being the smallest and Hyalophora cecropia the largest)
The members of this Genus are all large boldly patterned moths.
Although similar in appearance and pattern, this group is divided into 3 distinct species. In addition, there are several population groups of hybrid origin, each presenting taxonomic questions with regards to placement and relationships between and among the described parent species.

VARIABLE - refer to the following list of taxa:
In most parts of the range, the members of this Genus are univoltine. The adults are most frequently encountered between April and July. However, there are exceptions, and adults may be encountered earlier or later in the season, particularly in the southwestern USA and Mexico.

VARIABLE - refer to the following list of taxa:
Life Cycle
Holometabolous ("Complete Metamorphosis") = egg-larva-pupa-adult
VARIABLE - for species details, refer to the following links/list of taxa:

Additional NOTES regarding the various life stages: ECONOMIC SIGNIFICANCE (Pest, Medical significance, Venomous, … etc.)
Members of this Genus are not known to have any strong negative economic impacts on human agriculture or economy. In some instances, the larvae are considered “pesty” defoliators of fruit trees & ornamentals, however, there is no long term damage produced by the feeding habits of the larvae.

1. BENEFICIAL as an herbivore (“recycles” foliar cellulose and nutrients into frass = fertilizer)
2. BENEFICIAL as a member of the ecosystem (i.e. food chain)
3. One of North America’s most beautiful and impressive insect Genera and worth conserving!

The imposing larvae DO NOT sting; however, they do contain toxins & complex proteins in their hemolymph (blood), incl. a strong antibiotic, Attacin. When disturbed, the larvae will “bow up”, thrash from side to side and may release small droplets of hemolymph containing various toxins. This cocktail of chemicals often includes compounds derived from host foliage as well as the complex defensive proteins. In some instances, there may be severe reactions (incl. skin irritation, rash, burning & itching, watery eyes, runny nose, and sneezing - extreme reactions may include swelling and difficulty breathing). Individuals subjected to repeated or frequent exposure (usu. researchers & hobbyists) often develop allergic reactions to the cuticular hydrocarbons, body fluids, hemolymph, frass (poop & assoc. mold), and the adults’ wing scales. Prolonged exposure often increases one’s risk of sensitivity!

VARIABLE - refer to the following list of taxa:
There are 3 described species and several taxonomically enigmatic populations and hybrid groups.
For more info, refer to the Genus Hyalophora in The Wild Silk Moths of North America by Tuskes, Tuttle & Collins.

Eastern USA, Eastern Canada, and reported from ne. Mexico (?)

There are currently no subspecies recognized; however, this taxon is subject to geographic variation and there are recognized hybrid populations containing cecropia blends.


ne. USA, Great Lakes region of US & Canada, & much of e. Canada

USA & Canada / Rocky Mountains, Western Plains, and Great Basin e. of the Sierras

Hyalophora columbia ssp. gloveri ("var. nokomis")
Plains of Central Canada
Synonymized with gloveri. Described as being a diminutive & slightly divergent population. Specimens identified as nokomis often appear to possess cecropia influence...Given the distribution pattern, these populations liekly represent a blend zone(?)(NOTE: evident red post medial scaling and large dark spots submarginally on the forewings - both traits are often more typical of cecropia)

Rocky Mountains of the USA & Canada (High Elevations)
Synonymized with gloveri. Described as being a high altitude diminutive form. Specimens identified as reducta have been reported along the Rockies and are likely the result of environmentally induced traits. The small size and compact appearance does not seem to be genetic. Stocks collected at higher elevations and reared at lower ones seem to produce "normal sized and patterned adults".

sw. USA - incl. se. Arizona & sw. New Mexico - south into central Mexico


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)


Below are some examples of naturally occuring "intra/interspecific hybrids", "self-sustaining Hyalophora pop's of hybrid origin", and divergent groups with distinct characteristics.

Refer to the following: Natural Hybrids & Blend Zones
H. "cecropia x columbia gloveri" ("Western fringe cecropia"): Populations are scattered across the western Plains and eastern slopes of the Rockies (USA & Canada).
H. "cecropia x columbia gloveri var. nokomis": Plains of central Canada
H. "cecropia x columbia columbia": Occasional crosses occur in the northeast (USA & Canada)
H. "kasloensis" ("euryalus x columbia group"): Allied to euryalus but of hybrid origin
Hyalophora "Idaho hybrid complex" ("euryalus x gloveri"): c. Idaho / nr. Boise, Idaho
Hyalophora "Sierra/Monitor Pass hybrid complex" ("euryalus x gloveri"): Isolated canyons across the Sierra Nevada Mountains / esp. Monitor Pass, CA
Hyalophora columbia gloveri ("Mexican Variants): Populations are scattered across the mountains of the sw. USA (se. AZ/sw. NM) extending into central Mexico

Historically, members of this Genus have been crossed by hobbyists and entomologists alike. Many of the subsequent crosses have been instrumental in taxonomic studies.
Refer to the following: Lab Produced "Interspecific Crosses"

For more info on range maps and images, refer to the Genus Hyalophora in The Wild Silk Moths of North America by Tuskes, Tuttle & Collins.



"H. cecropia x gloveri" ("Western fringe cecropia moths"):
Generally accepted to be "H. cecropia", some Hyalophora populations in parts of Colorado, Wyoming, S. Dakota, N. Dakota, e. Montana & central Canada often produce incredible phenotypes suggestive of "cecropia x gloveri"(?).
*However, it's important to mention some of these moths may not be "hybrids" at all, but rather represent the phenotypic extremes within the cecropia taxon proper. Nonetheless, some of these localized populations seem to be self sustaining and remain quite unique in appearance.


"H. cecropia x gloveri var. nokomis":
Interesting populations can be found across central Canada where cecropia and columbia gloveri overlap. Many specimens identified as "H. gloveri ssp. nokomis" appear to possess traits typical of cecropia (i.e. red postmedial scaling and coloration).

"H. cecropia x columbia columbia":
These occasional crosses occur in the northeast (US & Canada)
For additional information on natural hybridization between cecropia & columbia in e. Canada, please refer to the following article: Bridgehouse, Derek W. A Case of Natural Hybridization Between Hyalophora cecropia and Hyalophora columbia (Lepidoptera: Saturniidae) in Nova Scotia, Northeastern Naturalist, 13(1):29-34, 2006.


"H. columbia columbia x gloveri" blend zones:
Because of natural "columbia-gloveri" blend zones in parts of ec. Canada, "gloveri" was synonymized with columbia.

*NOTE: A similar and more widespread pattern of blending between "gloveri" and "euryalus" suggests there may be a relationship between those taxa as well (?).

"H. columbia/gloveri x euryalus" blend zones:
Western states along the Sierras and upper parts of the Great Basin.
Refer to the following:
"Boise-Idaho Hyalophora complex (gloveri x euryalus blends)"
"Sierras-Monitor Pass Hyalophora complex (gloveri x euryalus blends)"

"H. kasloensis":
Hyalophora populations known as "kasloensis" from parts of the Pacific nw. are among the best known clinal members ("blends"?) and certainly deserving of some taxonomic recognition or status.


"Boise Idaho Hyalophora complex":
Another unique and apparently self sustaining population group thought to consist of "euryalus X gloveri" occupies a region across parts of the nw through Idaho.


"Monitor Pass gloveri x euryalus blends":
Sierra Nevadas of California


"Mexican & Sonoran gloveri":
Hyalophora pop's from the mountains of central Mexico north into the Sonoran region of n. Mexico & se. Arizona (sw. New Mexico) "appear to be" geographically & temporally restricted from most other Hyalophora. These populations deviate from other columbia/gloveri as follows:

1) Peak time of year for adult activity
(Often bivoltine with an active late July-August emergence and a smaller spring emergence between April-early June)

2) Slightly larger size
(often approaching that of cecropia)

3) Degree of coloration & pattern (refer to the images below for details)

a) Extensive reddish-burgandy coloration extending "submarginally" as seen in euryalus (instead of the softer gray coloration typical of most other "gloveri" populations). There has been some thought, this increase in reddish coloration may be environmentally induced. There is a tendency in several of the Hyalophora species to exhibit more red when exposed to warmer temperatures (less dramatic temp differentials between day and night = "more reds").
b) They exhibit tremendous variability in the shape and size of the discal crescents, ranging from long euryalus-like to short columbia/gloveri-like to absent in some examples.
c) The presence of a discernable red postmedial band - best viewed ventrally (as seen in cecropia)

NOTE: Specimens from central Mexico are often more striking and divergent in appearance.

Final Note: These members of the "columbia species group" often spark debate among specialists and hobbyists alike. "Are they possibly hybrids, a distinct subspecies or something else" ???

HYPOTHETICAL: In discussion with several hobbyists and Saturniid specialists, it is thought these moths may represent the closest living members to the Hyalophora "ancestor?"

I would like to thank the following people for their contributions ... sharing specimens, images, personal observations & experiences: Dr. M. Collins, S. Smith, D. Bridgehouse, P. White, D.J. Ferguson, Dr. J. Kruse, B. Oehlke, J.P. Perry, H. Pavulaan, R. Patterson, R. Otto, V. Brou, Z. Lemman, E. Rand, S. Bailey, & "shotguneddie" + many...many others for taking the time to share information, post images & share their comments here on bugguide.

Please continue to share; None of us are as good as all of us!
Bill Reynolds
Print References
Arnett and Jacques,(6)
Works Cited
1.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.
2.Peterson Field Guides: Eastern Moths
Charles V. Covell. 1984. Houghton Mifflin Company.
3.Moths of Western North America
Powell and Opler. 2009. UC Press.
4.The Moth Book
W.J. Holland. 1968. Dover.
5.Discovering Moths: Nighttime Jewels in Your Own Backyard
John Himmelman. 2002. Down East Books.
6.Simon & Schuster's Guide to Insects
Dr. Ross H. Arnett, Dr. Richard L. Jacques. 1981. Fireside.