Sphinx asellus courtesy of Bruce Walsh.

This site has been created by Bill Oehlke at oehlkew@islandtelecom.com
Comments, suggestions and/or additional information are welcomed by Bill.

TAXONOMY: Family: Sphingidae, Latreille, 1802 Subfamily: Sphinginae, Latreille, 1802 Tribe: Sphingini, Latreille, 1802 Genus: Sphinx Linnaeus, 1758 ........... Species: asellus (Rothschild & Jordan, 1903)

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DISTRIBUTION:

The Asella Sphinx Moth, Sphinx asellus (Wing span: 3 1/4 - 3 7/8 inches (8 - 9.9 cm)), flies in pinyon-juniper woodland and similar arid situations in Colorado (specimen type locality), Nevada, Utah, extreme southwestern Wyoming, Arizona, New Mexico and southwestern Texas.

It tends to be seen at elevations from 4000-6000 feet.

Sphinx asellus, resting on juniper, Payson, Gila County, Arizona,
July 24, 2009, courtesy of Lauren Paterson, tentative id by Bill Oehlke.

I have chosen asellus over chersis for the specimen depicted above, primarily because of the fine second pair of dark streaks on the thorax. I could be wrong!

The upperside of the forewing is pale silver-gray with a series of black dashes, a white patch at the tip, and a white stripe along the outer margin. The upperside of the hindwing is black with blurry white bands.

Sphinx asellus is very similar to Sphinx chersis, but asellus is smaller, paler, and has more white above the dark streaks of the forewing apex.

Jim Tuttle writes, "Sphinx chersis has a pair of single and very fine black lines running longitudinally along the thorax; whereas Sphinx asellus (Kitching & Cadiou changed it from asella) almost always has two sets of black lines - the inner lines tend to be bolder than in chersis - the outer (away from the center of the thorax and toward the wings) being very faint."

It is often very difficult to tell the two species apart as adult moths. The larvae, however, are quite distinct.

It is even very difficult for the leading experts to tell the two species apart when only pictures are available that do not show the hindwings or ventral surfaces. Jean Haxaire indicates the following Sphingidae is Sphinx chersis while Jim Tuttle says he would "GUESS" the image to be Sphinx asellus, based upon the boldness of the black lines, and even though the secondary lines are not visible in the picture.

Sphinx chersis/asellus (closer to chersis), Arizona, courtesy of Adam Fleishman.

FLIGHT TIMES:

Sphinx asellus adults probably fly as a single brood from from May-July.

ECLOSION:

Pupae probably wiggle to surface from subterranean chambers just prior to eclosion.

SCENTING AND MATING:

Females call in the males with a pheromone released from a gland at the tip of the abdomen. Adults nectar at a variety of flowers.

EGGS, LARVAE, PUPAE:

Larval hosts are Manzanita and Arctostaphylos of the Ericaceae family.

Sphinx asellus fifth instar, courtesy of Bruce Walsh.

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