Hummingbirds of the Night

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.

Pandorus Sphinx Moth
Creative Commons License photo credit: August Norman
 Pandorus sphinx

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

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

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.

tomato hornworm
Creative Commons License  photo credit: naturegirl 78
Tomato hornworm
(Manduca quinquemaculata)

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.

Mirabilis
Creative Commons License  photo credit: sigusr0
Four O’clock (note long tube)

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.)

Summer Encounters – Around the House

Green Anole on ti plant
Creative Commons License photo credit: mannyh808

Summertime in Houston has been very exciting for me. This is my second summer living here and each year I discover new animals.  Last year, I was thrilled to learn about Anoles, Mediterranean House Geckos, and of course, American Alligators. My first job at the Museum was to assist in teaching field camp during the summer for our Xplorations program.  I quickly became familiar with the wildlife of Houston’s surrounding areas along with learning how to survive the heat and humidity while hiking.  My previous experiences with animals in Oregon and New Mexico did not prepare me for the entirely different array of wildlife here in the South.

Tersa Sphinx caterpillar
Tersa Sphinx caterpillar

My first encounter with a new animal this summer happened in my own back yard. On my small butterfly bush, I happened accross a very large, brown, spotted caterpillar.  Since childhood I have had a fascination with these lovely little insects and so I promptly ran inside to get my camera to document my find.  I later had the caterpillar identified by one of the Museum’s entomologists, Laurie.  She quickly ID’d my caterpillar to be a Tersa Sphinx, Xylophanes tersa.  I was amazed at the size of this butterfly larva.  After enduring the bites of the huge zebra-striped mosquitoes and now seeing this large caterpillar, I was once again reminded that everything’s bigger in Texas.

On the other hand, last month we were asked to identify a tiny, writhing, worm-like creature.  It was found near our office which added to the curiosity of this animal.  It was only about 2 inches long, very smooth, not slimy, and appeared to have scales with a pointy tip for a tail.  Was it a type of worm?  The diminutive size and shape suggested worm, but it was somewhat hard to the touch, a bit shiny, and without any of the mucous normally occuring with worms.  Could it be a caecilian?  No, those don’t live in Texas and would definitely be slimy.  Could it be a very tiny snake baby?  Aha! Perhaps we were getting somewhere.

Texas Blind Snake
Texas Blind Snake, Leptotyphlops dulcis

After consulting with my friend who’s an herpatologist by hobby (thanks, Ira!), we discovered that we did indeed have our hands on a tiny snake.   Judging by its size & character, this itty-bitty critter was a juvenile Texas Blind Snake, Leptotyphlops dulcis.  I was reassured of this animal being a snake when I noticed it would occasionally stick out its tongue.  This small serpent would only grow to be about 8 inches in length, by far the smallest snake I have ever had the pleasure of meeting.  Many Texans may come across this snake in their gardens under logs or bushes, mistaking it for a worm.   It emerges from its hiding place in the soil to feed on termite and ant larvae, making it a welcome hunter to any gardener.  Like many other native species, it has been adversely affected by the red imported fire ant

Update. The BBC has published an article on 8/4/08 about the world’s smallest snake, Leptotyphlops carlae, found in Barbados.  This smaller relative to the Texas Blind Snake will only reach 4 inches at maturity, half the size of our native Leptotyphlops dulcis.

The final animal I’d like to share today is the first new mammal I’ve seen in Houston.  Much to my dismay, my dogs (Sasha & Dione) like to dig holes in our backyard.  Dione is quick enough to catch any unfortunate animals that may happen to find themselves in her territory.  As fas as I can tell, she is more interested in playing with the animals than eating them.  One evening, she finally managed to dig up an Eastern mole, Scalopus aquaticus.  I’m sure she’s been hunting them for a while, hence all the holes in our yard.  I rescued the poor mole from the dogs and brought it inside to investigate as I’ve never seen one until now.  It was covered in slobber so I wasn’t able to enjoy the silky smooth coat that is a normal characteristic of moles.

Mole
Eastern Mole, Scalopus aquaticus

The most amazing feature of this mole were its feet.  The front feet are very large, broad, paddle-shaped feet with webbing between the toes – perfect for digging.  In comparison, the hind feet were very small, similar to those of a mouse.  The mole’s eyes, ears, and nose also indicated a subterrestrial life.  We were unable to see any eyes or ears through its fur.  There really isn’t much to see underground and protruding ears would simply get in the way of digging. The nose was long and sensitive, great for smelling prey in the dark.  One type of mole, the Star-Nosed Mole, has an extremely sensitive sniffer.  It has even been found to sniff underwater.  Our Eastern Mole may not be able to smell underwater, but they do consume a great many invertebrates that can be potentially damaging to plants.

If you have crossed paths with an unfamiliar Texas animal, please share with us as we enjoy hearing about other people’s experiences.  Look for Summer Encounters – Brazos Bend State Park as my next blog post when I share some of my adventures in hiking around BBSP roasting alligators and hunting marshmallows….oops.  Well, you know what I mean.