Lettered Sphinx Moth: All You Need to Know in a Nutshell

The lettered sphinx moth is a fascinating creature, known for its unique appearance and early emergence in the spring season. As one of the first sphinx moths to be seen, they can be found in various parts of the United States from March through July, making them a common sight for many nature enthusiasts during this time frame source.

These moths have distinctive features, such as their deeply scalloped forewing margins and the male’s tendency to curl their abdomen upward. Their wing coloration patterns also help to identify them, with tan or brown being the most common shade. On a closer look, you’ll notice the unique patterns on their wings that resemble letters, hence their name source. In the world of moths, the lettered sphinx plays a critical role as a pollinator and a source of intrigue for those interested in learning more about these amazing insects.

Physical Characteristics

Size and Color

The lettered sphinx moth (Deidamia inscriptum) is a member of the Sphingidae family and is known for its distinct size and color patterns. These moths are medium-sized, with features that include:

• Overall tan or brown coloration in male and female moths
• Males often have the abdomen curled upwards¹
• Deeply scalloped forewing margins, contributing to their unique appearance¹

Streamlined Bodies and Narrow Wings

Sphinx moths, including the lettered sphinx, have streamlined bodies and narrow wings. These features enable the moths to be agile and efficient fliers:

• Long, pointed abdomens characteristic of most Sphinx moths²
• Long, narrow forewings, with some species having angular and irregular margins²

Antennae and Proboscis

The lettered sphinx moth, like other members of its family, has specific antennae and proboscis features:

• Antennae that gradually widen and then narrow again towards the tip²
• Comb-like extensions on the antennae²
• A long proboscis (mouth tube or “tongue”) used for feeding on nectar from flowers²

Comparison Table: Lettered Sphinx Moth vs. White-Lined Sphinx Moth

Habitat and Range

Geographical Distribution

The lettered sphinx moth can be found in various parts of North America, including the U.S., Canada, and Mexico. In the U.S., they are widely distributed, ranging from South Carolina and Florida to as far north as Ontario and Quebec in Canada.

Preferred Environment

These moths prefer habitats with abundant flowering plants, as they feed on nectar. They are most commonly found in open woodlands, meadows, and gardens. Below are some features of their preferred environments:

• Open woodlands
• Meadows
• Gardens with flowering plants

The lettered sphinx moth has a broad distribution, making it an interesting species to study and observe across North America.

Behavior and Adaptations

Flight and Hovering

The Lettered Sphinx Moth showcases remarkable flight and hovering capabilities, much like a hummingbird. They are known for their:

• Long, pointed forewings
• Heavy body and pointed abdomen

This design allows them to:

• Hover near flowers
• Feed on nectar via a very long proboscis

Active Times and Migratory Patterns

Sphinx moths, including the Lettered Sphinx Moth, are generally nocturnal creatures. Key points about their habits include the sensitivity to weather patterns and the occurrence of seasonal migrations.

Weather-induced behavior:

• More active during warmer months
• Favor calm weather, avoid strong winds

Migratory patterns:

• Often depend on local flora
• Concentrations may follow ripples, waves, crescents, and curled patterns

Comparison table of Lettered Sphinx Moth behaviors:

Diet and Pollination

Caterpillars and Food Plants

• Lepidoptera: Lettered sphinx moths are part of the Lepidoptera order, which includes butterflies and moths.
• Caterpillars: The caterpillars of this species, called hornworms, grow to about 25mm to 38mm in length.
• Food plants: Common food plants for lettered sphinx moth caterpillars include Virginia creeper and grapevines.

The caterpillars’ feeding habits enable them to utilize two important food resources: Virginia creeper and grapevine leaves.

Adult Moths and Nectar

Adult lettered sphinx moths, like their clearwing counterparts, feed on nectar from various flowers. This feeding pattern allows them to consume essential nutrients and energy. They are known for their long proboscis, which helps them access nectar from deep within flowers.

Role in Pollination

• Pollinators: Sphinx moths, such as the lettered sphinx, are important pollinators for numerous plant species.
• Nocturnal habits: These moths are active during the night, pollinating a wide variety of night-blooming flowers

As they visit different flowers to consume nectar, the moths inadvertently transfer pollen from one plant to another, aiding in their reproduction.

Comparison Table: Caterpillars vs. Adult Moths

In summary, lettered sphinx moths are important pollinators, with their caterpillars feeding on food plants like Virginia creeper and grapevines, and adults consuming nectar from various flowers. These unique features make them a fascinating species to study and observe.

Life Cycle and Reproduction

Mating Habits

The lettered sphinx (Deidamia inscriptum) is an insect in the order Lepidoptera, belonging to the sphinx moth family. These moths exhibit unique mating habits, in which males are attracted to a female through the use of chemical pheromones. Mating usually takes place at night, as these are nocturnal creatures.

Eggs and Larvae

After successful mating, the female moth lays her eggs on the host plants, preferring larval food sources such as grapes and Virginia creeper. The eggs hatch into larvae, commonly known as caterpillars. These caterpillars feed on their host plant and undergo a series of molts as they grow. Some features of the larvae include:

• A soft and elongated body
• Distinctive markings on their skin
• A horn-like structure on the posterior end

Pupation and Metamorphosis

As the caterpillars reach their final instar, they start the process of pupation. They find a suitable location, often in leaf litter or soil, to form their pupal cases. Within this protective cocoon, the transformation, or metamorphosis, occurs. The lettered sphinx moth then emerges as an adult with the following features:

• A proboscis: a long, tube-like mouthpart used for feeding on nectar from flowers
• Long and pointed forewings
• A wingspan ranging from 2.4 to 3.5 inches
• A hovering flight pattern similar to hummingbirds (earning them the nickname “hummingbird moths”)

Comparing lettered sphinx moths with the related white-lined sphinx (Hyles lineata):

For more information on lettered sphinx moths, their life cycle, and reproduction, visit insectidentification.org.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Lettered Sphinxes and a Gnome

first sphingidae of spring
I spotted and collected my first sphinx moths of the year on Sunday (3/18). I found out they are Lettered Sphinx moths, Deidamia inscripta, from bugguide.net. I was scrolling through your marvelous collection of sphinx images, and I didn’t see any of this species, so I thought you might like to check these out. (And the female laid eggs the night I collected them!) Going to be a good year for moths! Anyways, keep up the great work, bugman!!
Bobby

Hi Bobby,
Your amusing photo of Lettered Sphinxes just made our day. It is awesome.

Letter 2 – Lettered Sphinx

Bug identification
I am curious about a small brown insect that lived on our garage wall for a brief time. He is very tolerant of photographers. Two friends have identified him from your website as a sphinx moth or a Spotted Apatelodes Moth. You may use the photos on your website if any of them would be useful. He was in Chadds Ford, PA on May 2-3, 2008. He stayed about 36 hours. What do you think he is? Thanks for the help –
Judy Cz

hi Judy,
We are ecstatic to have received your images of a Lettered Sphinx, Deidamia inscriptum. In his excellent website, Bill Oehlke describes the male as resting with a stongly curved abdomen, just like your specimen.

Letter 3 – Lettered Sphinxes

Lettered Sphinx Moth Trio
Location:  Cosby, Tennessee
May 1, 2011
Hi Daniel,
These moths are plentiful this season in Cosby, TN.  It took me a while to identify them, but not too long…page 21 on your (hawk moth) site!
This, tiny winged critter?  I haven’t had any luck identifying it.
I am always amazed, intrigued, and awed by the detail of each insect that I photograph.  Thank you for helping me learn more about them all.
R. G. Marion
Sevier County, TN

Hi again R.G.,
While we applaud your efforts to muddle through our labyrinthine archives to identify some species, we often provide links to websites with more specificity.  In our opinion, the best place to search for Sphinx Moth species identification is the Sphingidae of the Americas website which has an excellent information page on the Lettered Sphinx, Deidamia inscriptum.  From the nation page, you can select the country of origin and from the Sphingidae of the United States page you can select the state of origin which helps to significantly narrow down the identification process.  This photo of a trio of Lettered Sphinxes is quite amusing.  Your other insect is a species of Mayfly.

Letter 4 – Lettered Sphinx

Subject: Moth
Location: Ribgwood, NJ
May 5, 2013 12:17 pm
I found this moth that appears to have a horn on ots back. Peculiar!
Signature: Christy

Hi Christy,
Though your photo is blurry, we believe we have correctly identified your moth as a Lettered Sphinx, Deidamia inscriptum, thanks to photos posted on the Sphingidae of the Americas website.  The site states:  “Males rest with the typical strong curve to the abdomen,” which indicates your individual is a male.  Did you by chance mean Ringwood, New Jersey?

Hello. I am so sorry. Yes, Ringwood.
Sorry it is blurry. I was trying to get close without it flying away. I think it is still there. Very cool!!!

Letter 5 – Nasty Reader Award #12: Lettered Sphinx … in Nevada!!!

Ed. Note:  Despite the signature, this is NOT an inside job

Subject: Angry moth in northern Nevada
Location: Northern Nevada
January 10, 2017 3:56 pm
Hey asshole, if you spent as much time crafting mocking replies to your so-called “””nasty readers””” as you do researching what species the bugs are, you wouldn’t HAVE any angry clients. Take my email adress OFF my submission, I dont need more spam. I dont care what your “terms and conditions” are.
Signature: Daniel Marlos

Dear Trashface, AKA Daniel Marlos impersonator,
We were so stunned by your virulent letter with its inflammatory image that there is no question in our mind that you deserve the Nasty Reader tag, and we strongly suspect that you are deliberately vying for that coveted award.  Your efforts have paid off.  Your assessment that we spend much more time researching submissions to our site than we do “crafting mocking replies” to our “so-called “”nasty readers””” is absolutely correct.  Since your letter is only the 12th Nasty Reader we have tagged in our 15 years of running What’s That Bug?, a site currently with  23,437 unique postings, only .051% of our responses were to readers deemed by us to be nasty.  We don’t believe we have that many angry readers, and we can deal with those odds as we learned long ago that “you can’t please all the people all the time.”
That stated, we are ready to get down to identifying your Sphinx Moth from the family Sphingidae, and trust us when we say we spent a great deal more time with that task than we did crafting our first paragraph in response to you.  We could not locate your moth in the Sphingidae of Nevada, the Sphingidae of California, nor the Sphingidae of Idaho pages of Bill Oehlke’s awesome Sphingidae of the Americas site.  At that point we contacted Lepidopterist Julian Donahue who confirmed the family Sphingidae, but neither he nor Eric Eaton were able to provide a species name.  We wrote to Bill Oehlke and he provided us with the correct identification.

Bill Oehlke identifies Deidamia inscriptum
Daniel,
It is Deidamia inscriptum. I have not seen any previous reports from Nevada, but it is known for sure from eastern Texas all the way to the east coast so it may well be in Nevada and just hasn’t been documented there before. It is also possible that it was inadvertently imported into Nevada as a pupa in soil at base of some potted plant that was transported across state lines. Maybe a storm with high winds brought it to Nevada. Maybe it is a hoax. You could just indicate it is Deidamia inscriptum which is not native to Nevada. Do you have a more precise location in Nevada?
The Sphingidae are strong fliers and can get energy from flower nectar or fermenting fruit, so it might even have flown there, but it appears to be a fresh specimen, so my guess is it is a wrong location or an accidental import. Maybe it came in the soil as pupa in a potted Christmas plant.
Hope you had a great holiday season and have a great new year. Time flies.
Bill

Thanks to Bill Oehlke’s identification, we were able to locate the Lettered Sphinx on the Sphingidae of the Americas site, and we learned that it “flies from New Hampshire south to northern Florida and southern Alabama (Houston County (JS)); west to Minnesota, Nebraska, Oklahoma, and Texas. The specimen type locality is Indiana. It also flies in southern Ontario and is occasionally seen in southern Quebec” and “In Greek literature, Deidamia was one of Lycomedes’ daughters, and she bore a son, Neoptolemus, for Achilles.  The species name ‘inscriptum’ MAY ? have been chosen for the parallel ‘lines’ on the forewings, suggesting lines of script.”   Now that we have determined that you are in fact among the minute percentage of our readership that might be considered “angry clients” that we refer to as Nasty Readers, and that the identity of your moth is Deidamia inscriptum, the mystery remaining for us is how did it stray so far from its typical range?  Bill Oehlke has offered some plausible reasons, and we don’t want to discount that you may have been trying to stump us as well as to taunt us, and that perhaps this image was taken someplace other than Nevada.  We will most likely never know.  Congratulations again on being awarded with our 12th Nasty Reader designation.
P.S.  We will not be posting your “email adress” as we do NOT post email addresses, so we are not responsible for your spam.

Trashface writes back and fesses up to internet plagiarism as well as being angry and a poor writer
First of all, you need to grow a thicker skin if you get offended by mean emails.
And secondly, don’t be a smart-ass. You know very well that I meant to say “if you spent as much time identifying bugs as you do crafting mocking replies…etc.”
But clearly wits aren’t your forte. A cleverer person than you would’ve realized that I just Google image searched “bug on middle finger” to find an offensive yet hilariously topical picture to send to you. I stole the pic from Flickr, which you probably think is deplorable too. Congrats on wasting time identifying a bug that I didn’t even take a photo of.
Bugger off, bug man

Ed. Note:  Far be it from us to assume what our readers mean to write when they send in inquiries.  We take their writing for face value and we do not correct their errors.  We had no luck locating the FlickR posting where this image was allegedly pilfered as we want to request permission from the actual photographer to keep it on our site.

From Our Facebook Fans:

Jeff Lanterman
January 12 at 10:56am
Did he think that was funny? Sometimes I don’t understand people.

Sean Gaukroger
January 12 at 12:59pm
Huh? Today’s Sphinx moth brought to you by the letter “F”?

Lisa Phillips
January 12 at 2:54pm
Thank you for the identification & sorry this person is rude. I myself look forward to your posts. Keep up your fascinating work ?

Heather Christensen
January 12 at 3:49pm
We love your posts! I have not yet submitted any critters needing identification, but my son and I always keep our eye out. This guy is a clown, and definitely deserves the coveted “Nasty Reader” title. Keep up the great work, we love you guys. ???????

2017/01/12/nasty-reader-award-12-lettered-sphinx-nevada/

Letter 6 – Lettered Sphinx

Subject: Bugs in yard
Location: Massachusetts
May 19, 2017 3:11 pm
Been trying to identify these bugs in my yars
Signature: Shaun Hose

Dear Shaun,
With its subtle markings, the Lettered Sphinx, Deidamia inscriptum, is quite an understated beauty.  According to the Sphingidae of the Americas:  “Males rest with the typical strong curve to the abdomen, …. This is usually one of the earliest Sphingids to fly each season.”  The upward curved abdomen visible in your image indicates your individual is a male of the species.