Other Common Names
Big Poplar Sphinx - name not recommended (see Remarks section below)
Synonyms and other taxonomic changes
Pachysphinx modesta (Harris)
Orig. Comb: Smerinthus modesta Harris 1839
Explanation of Names
modesta - when seen facing up on a wall, the bottom half of the moth is dark, as though "modestly covered" by a cloak or shawl
Adult: forewing gray with basal third lighter; outer third sometimes light also, leaving just median band dark
hindwing gray with crimson patch and inward-pointing bluish-black triangle near outer margin
Larva: pale green, rarely brown or orangish; white granulose spots arranged in rings around body; head flattened, triangle pinkish, bounded laterally by pale band from eyes to vertex; 3 to 6 midabdominal oblique yellow stripes, most conspicuous on second, third, and fourth segments; each stripe continued back onto adjoining segment; broader oblique pale stripe extending from prolegs on sixth segment onto shortened horn
[description by David Wagner and Valerie Giles]
Much of North America: from British Columbia to Nova Scotia, south to northern Florida, west to Texas, Oregon, New Mexico. Absent from California, Arizona, Nevada, and the arctic.
Along rivers and on moist mountainsides; generally, anywhere the host plants grow.
adults fly in June and July in the north; April to September in Gulf states
larvae present July to November
larvae feed on leaves of poplar, aspen, cottonwood (all Populus spp.), and willow (Salix spp.)
adults do not feed
eggs laid on leaves of host plant hatch in about 9 days; overwinters as a pupa in shallow burrow in the ground; two generations per year in the south, one in the north
Life cycle photos:
1.eggs 2.early instar larva 3.older larva 4.last instar larva 5.pupae 6.mated pair
There is confusion regarding the common name. Holland's 1904 publication, Covell's Guide, and the recent Audubon Guide calls P. modesta the Big Poplar Sphinx but that name is used only for P. occidentalis by the Butterflies and Moths of North America site and several other sources. Since both species are called Big Poplar Sphinx by various sources, it would be less confusing if that name were not used at all, and replaced with either Modest Sphinx (for P. modesta) or Western Poplar Sphinx (for P. occidentalis).
The Modest Sphinx (Pachysphinx modesta) occurs coast to coast in North America, whereas the Western Poplar Sphinx (P. occidentalis) is restricted to western North America.
Western Poplar Sphinx
occurs only west of Texas and North Dakota; its light form has pale brownish-yellow forewings, and its dark form has blacker lines that contrast more against ground color of forewing; black line on hindwing does not form a distinct triangle (compare images
of light form with P. modesta
at CBIF, and see images of dark and light forms
by Bruce Walsh, Arizona)
live adult, larva, and pupa images
- Bill Oehlke, silkmoths.bizland.com
distribution in Canada
list of provinces (CBIF)