A few nights ago I saw what I thought was a hummingbird – out way past its bedtime – whirring around the fragrant, long-tubed blooms of the Rangoon creeper in my back yard. As I watched, several more of these curfew-breakers appeared, working the flowers all up and down the fence. I soon realized that these were not in fact hummingbirds, but were their nocturnal analogs: hawk moths or sphinx moths.
Talk about convergence! If they hadn’t been flying at night – and there are some day-flying sphinx moths, by the way – I would have been hard put to tell they weren’t ruby-throated hummers (the most common hummingbird species in our area). The sphinx moth in question (probably the five-spotted hawkmoth, Manduca quinquemaculata) is about the same size and shape as a ruby-throat, with a bullet-shaped, streamlined body, and has exactly the same behavior. The powerful wings of both hummers and sphinx moths beat so swiftly (up to 50 or so beats per second) that they are just a blur in flight. Both can hover up, down, back and forth, helicopter-like. Instead of a hummingbird’s long bill, sphinx moths have a long tongue or proboscis, kept rolled up when not in use and extended when reaching for nectar at the base of a long-tubed flower.
Rangoon creeper - flowers are first white, turning red the next morning
Both hummers and sphinx moths are important pollinators, and certain plants have evolved flowers that are specifically “designed” to attract these powerful fliers with their long beaks or tongues. Such flowers typically have abundant nectar at the base of elongated floral tubes (the bottom part of the petals grows together to form a hollow tube). But while hummingbird flowers are usually brightly colored (especially red) and often do not have any scent (since hummingbirds can’t smell), moth-pollinated flowers are typically white or pale-colored, and often emit a strong, sweet scent as the sun goes down.
The family of sphinx moths, the Sphingidae, is a large one, with about 1200 species world-wide (most are tropical). There are about 60 species of sphinx moths in North America, several of which occur locally. Some of the most common species in our area are the Five-spotted sphinx, the Carolina sphinx, the Rustic sphinx, the Pink-spotted hawkmoth, White-lined sphinx, Tersa sphinx, Vine sphinx, and Pandorus sphinx.
Another spectacular species, which occasionally ranges up from the tropics into our area, is the Giant sphinx. This very large moth (over six inches across) is notable as the pollinator of the rare ghost orchid of Florida’s swamps, Dendrophylax lindenii. Made famous in the book “The Orchid Thief” on which the movie “Adaptation” was based, this orchid has an extremely long, thin floral tube and depends on the giant sphinx moth to transfer pollen from one bloom to another in order to reproduce. Take a look at the specimen of the giant sphinx from our collection. Uncoiled, its tongue is almost nine inches long, almost twice as long as its body!
Giant sphinx moth with proboscis extended
This moth is the New World equivalent of the renowned “Darwin’s moth.” As the story goes, when in Madagascar, Charles Darwin saw the orchid Angraecum sesquipidale (rather similar to the ghost orchid). He postulated that there must be a moth with a tongue of equal length to the orchid’s 11 inch nectar spur that would serve as its pollinator. Sure enough, 41 years later (long after Darwin’s death), such a moth was discovered and its common name acknowledges his prescience.
Sphinx moth caterpillars are called “hornworms” because most of them have a distinctive horn that sticks up at the end of their abdomen. If you are a gardener you may have encountered large, green hornworms devouring the foliage of your tomato plants; these turn into the five-spotted hawkmoth I saw visiting my Rangoon creeper. Another hornworm frequently seen in the garden (if you grow pentas or star-flower) is the caterpillar of the Tersa sphinx, Xylophanes tersa. This caterpillar turns from green to brown as it grows, and has a pair of dramatic eyespots on its thorax. People sometimes confuse it with the caterpillar of the spicebush swallowtail. While hornworms can eat a lot of foliage, I confess that in my garden they are welcome to it – I like the adult moths too much to consider destroying their destructive “baby” stage… Besides, I think the caterpillars themselves are rather handsome!
If you find a hornworm and want to rear it, be sure to provide it with a couple of inches of loose soil when it gets large enough to pupate. Most sphinx moths pupate in the soil, and do not spin cocoons around the brown pupa. Some sphinx pupae have the tongue pulled away from the body, resembling the handle on a pitcher or Greek vase! Don’t disturb the caterpillar/pupa for several days after it burrows down or you may disrupt the pupation process.
Whether or not you get into the caterpillars, it is always a thrill to see an adult sphinx moth in action. To attract these nocturnal hummingbirds to your garden, consider planting some of the following. As an added benefit, you’ll enjoy the wonderful fragrance on evenings when these plants are in flower.
Angel’s trumpet (Brugmansia candida)
Jimsonweed or Datura (Daturaspp.)
Night-blooming jasmine (Cestrum nocturnum)
Rangoon creeper (Quisqualis indica)
Moon flower (Ipomea alba)
Four O’clocks (Mirabilis spp.)
Evening primrose (Oenothera spp.)
Petunias (Petunia spp.)