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)
Subspecies euryalus (Ceanothus Silkmoth)
Explanation of Names
EURYALUS: from the Greek "eurys" (broad) + the Latin "ala" (wing)
Size
Wingspan 89-127 mm
Identification
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 subspecies is highly variable in color and pattern across its range (Pacific coastal regions of B.C. Canada, the US, extending south into c. Mex.). 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]
Range
British Columbia, Canada south through the west coast states of the USA into Baja California (c. Mexico).
VARIABLE: adults are usually active from January to July, depending on altitude, latitude, and seasonal variation
larvae in July and August
Food
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
Remarks
The range of Hyalophora euryalus euryalus overlaps with H. "kasloensis", H. columbia (and its subspecies H. c. gloveri); hybridization often occurs where the various taxa meet.
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.)
The nominate race is highly variable in color and pattern. These observed differences are thought to be the results of climatic fluctuations, geographic origin and genetic variance among populations.
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)
Introgression, also known as introgressive hybridization, is defined as the movement of a genes from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. This information was obtained at the following: introgression.
Much of the information used on this guide page was contributed by the following:
Original guide for euryalus, Contributed by Cotinis on 6 February, 2006 - 3:46am
Additional contributions for original "euryalus guide page" made by Robin McLeod, Chuck Entz, Ted Kropiewnicki, William H. Reynolds, & Randy Hardy
I would like to personally thank the following people for their contributions ... sharing specimens, images, personal observations & experiences: Dr. M. Collins, S. Smith, D. Bridghouse, Dr. J. Kruse, B. Oehlke & "shotguneddie" + many...many others for taking the time to post images & share their comments & posts.
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)
Introgression, also known as introgressive hybridization, is defined as the movement of a genes from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. This information was obtained at the following: introgression.
With rare exception (Mexican & Sonoran forms), Glover's Silkmoth LACKS the maroon or purplish shading beyond PM line of wings and the hindwing discal spots are usually not as elongated.
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.
*Compare additional images of euryalus and cecropia. (NOTE: Middle image identified as euryalus is suspect...??)
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)
