Sphinx Moths

Hornworms in Culp Valley

If you’ve been up to Culp Valley or any nearby areas in ABDSP lately, you may have seen some bright caterpillars on plants or even inching their way across the road. These expressive green guys are known as hornworms. They acquired the name hornworm because of the stiff pointy dorsal near the end of their last body segment. Another common name for them are Tomato Hornworms, because they can quickly eat their way through tomato plants.

When the caterpillar is mature enough, it will dig itself into the sand and bury itself in a hard chrysalis shell. Through metamorphosis, the bright colored caterpillar larvae will turn into a Sphinx moth or Hawk Moth. When the moths are ready to emerge, the pupae wiggle themselves up to the surface of the sand or dirt, so the new moth has an easy exit.

There are over 100 different species of Sphinx moths in the US alone, the most common types here in the desert are the White lined Sphinx Moth, and the Tomato Hornworm. The White-Lined Sphinx moth is the most common widespread sphinx in America, north of Mexico. The name Sphinx moth relates to the defensive posture of the caterpillar which tucks its head down and raises its rump, slightly resembles a sitting Sphinx. Adult Sphinx moths are often called Hummingbird Moths because of the noise their beating wings make and they some are around the same size.


The sphinx also pollinates several types of flowers and plants. It sips nectar from a variety of flowers, and has a long tubular mouthpart, called the proboscis that is sometimes up to four inches long. These guys may be small but they can eat their way through a lot of plants in a small amount of time. Some years, the caterpillars occur in thousands and eat almost every plant in sight. They prefer evening primrose, but will eat a variety of plants, often until there’s nothing left.

The Sphinx moths are mostly active during the spring or fall. Mass migrations of hornworms can occur in spring with the wildflower season, and again in summer after heavy monsoonal rains, which explains why these bright guys have been crawling around. Keep an eye out, and soon the big, beautiful Sphinx moths will be out, pollinating flowers and plants as they go.

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