Sphinx moths (also called hawk moths and hummingbird moths) belong to a large family, Sphingidae, with about 1450 species. These are large moths with wingspans up to six inches.
Most common in the Tucson area is the White-lined sphinx moth (Hyles lineata) which has a wingspan of up to 5 inches and a body length of up to 3.5 inches. Its range extends from Central America, throughout the U.S. and into southern Canada. These moths are often mistaken for hummingbirds at first glance because they are about the same size and behave much like hummingbirds. They are fast flyers and can hover at a flower to sip nectar with their very long tongues; and they can fly side-to-side, and backwards. These moths are mainly nocturnal but may be about during daylight hours. The first generation adults appear in mid-May, with subsequent generations appearing throughout the summer. See good close-up photos of the adult moth and caterpillar here.
Adults females lay eggs generally on the underside of leaves upon which they feed. The eggs hatch into the larval stage – caterpillars. The sphinx moth caterpillar, which can be up to 5 inches long, is generally bright green with dark spots, but it can also be almost completely black or striped yellow and brownish. It has a large (harmless) hook on its back end similar to a tomato “hookworm.” According to DesertUSA, the name “sphinx moth” derives from the behavior of the caterpillar. “When alarmed, these larvae rear up their heads in a threatening sphinx-like posture and may emit a thick, green substance from their mouths.”
To complete pupation, the caterpillars dig burrows. Pupation can last from two weeks to several months depending on species and conditions. The adults moths dig themselves out from underground and may mate soon thereafter. According to DesertUSA, “In the Sonoran and Chihuahuan deserts, there may be two broods, one in the spring and another in summer. In the colder Great Basin desert, only one brood is produced.” In some species, if pupation begins in the Fall, it will last all winter with adults emerging in the Spring.
The moths feed exclusively on nectar and seek out flowers which have large supplies. This includes the evening primrose (see my ADI primrose article and a photo of the long tongue of a sphinx moth.) Some species can be harmful to crops.
According to a study at the University of Arizona, the Tohono O’odham would harvest the caterpillars, dry and braid them and use them as food. The study says that the caterpillars are not poisonous, but warns that eating too many will result in an upset stomach. (It doesn’t say how many are too many.)