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Subspecies Hyalophora columbia columbia - Columbia Silkmoth

Columbia Silkmoth - Hyalophora columbia - male Moth - Hyalophora columbia - male Hyalophora columbia (columbia) - Hyalophora columbia - male Hyalophora columbia - male Hyalophora columbia - male  Hyalophora columbia - Hyalophora columbia 7768_Columbia Silkmoth Female_Hyalophora columbia - Hyalophora columbia - female Hyalophora columbia
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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 columbia (Columbia Silkmoth - Hodges#7768)
Subspecies columbia (Columbia Silkmoth)
Other Common Names
Columbia Moth
Larch Silkworm (larva)
Nominate columbia occurs in tamarack forests across the Eastern Maritime Provinces of Canada (Nova Scotia, P.E.I., etc) and adjacent northeastern United States (New England & upstate NY), west into the Great Lakes region of the US & Canada. There is a zone of limited "blending with gloveri" along the periphery of the forests and eastern Plains of Canada (wc. Ontario possibly extending west into eastern Manitoba). The extent and compatability of blending remains in debate.
forests with poorly drained, boggy, acidic soil; suburban gardens; wide variety of wooded habitats
adults fly from May to June (early July?)
larvae from June-August (early Sept?)
In eastern North America [ssp. columbia], the preferred food of larvae is Tamarack (American Larch - Larix laricina)

In the west where columbia is suspected to blend with "gloveri" [ssp. gloveri], the larvae are known to eat leaves of Alder (Alnus sp.), Birch (Betula sp.), Antelope Bitterbrush (Purshia tridentata), Buckbrush (Ceanothus sp.), Buffaloberry (Shepherdia sp.), Plum & Cherry (Prunus sp.), Rose (Rosa sp.), Russian Olive (Eleagnus angustifolius), Willow (Salix sp.), etc.

Some of the above hosts have also been used to rear nominate columbia in captivity with limited success.
Life Cycle
one generation per year; eggs are laid singly on food plant, and hatch in 8-19 days, depending on temperature; overwinters as a pupa in spindle-shaped cocoon attached lengthwise to twig or trunk of tree or shrub
The taxon H. columbia currently includes 2 subspecies and several variants:
There is continued debate regarding the taxonomic relationships between the "gloveri group" and the "columbia nominate group".

"Columbia Group"

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

"Gloveri Group"

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

Plains of Central Canada
Synonymized with gloveri
Form "nokomis" is often described as being a diminutive & slightly divergent population from the nominate gloveri. Many specimens identified as nokomis often appear to possess characteristics suggestive of cecropia influence, particularly red scaling along the postmedial bands ...... possible blend zone???. Additionally, the range and locality data for many specimens identified as "nokomis" originate from areas of likely contact between the potential parent taxa - "cecropia x gloveri"
NOTE: The specimen pictured in the link below is strikingly similar to many "cecropia x gloveri" hybrids and blends

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

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.

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" ???
Internet References

live images of all life stages plus common name reference [Columbia Moth], distribution, description, food plants, biology, and other info (Bill Oehlke, Prince Edward Island)
live adult and larva images plus common name reference [Columbia Silkmoth] (Moth Photographers Group)