Modest Sphinx Moth: All You Need to Know – Quick and Easy Guide

The Modest Sphinx Moth is an interesting and unique species of moth that is often overlooked due to its nocturnal habits. These fascinating creatures are part of the Sphingidae family, known for their large size, heavy bodies, and long, pointed abdomens source. They demonstrate impressive flying skills, as they can quickly dart through the air and hover near flowers to feed on nectar using their long proboscis.

These moths are not only skilled fliers, but they also play an important ecological role as pollinators. Their caterpillars have a distinct appearance, characterized by their large size, colorful patterns, small rear horns, and strong legs that help them cling to plants source. Commonly referred to as hornworms, these caterpillars tend to rest on branches in a position reminiscent of a sphinx, giving rise to the name of this fascinating moth species.

Modest Sphinx Moth: Basic Facts

Scientific Classification and Name

The Modest Sphinx Moth belongs to the order Lepidoptera, family Sphingidae. The scientific name is Pachysphinx modesta, first described by Thaddeus William Harris. Common synonyms include Smerinthus modesta.

Physical Characteristics

The Modest Sphinx Moth is known for its gray, brown, and black colors. The adult moth has a furry and hairy appearance. The length of adults varies, but they generally have a wingspan of around 3.5 to 4.5 inches. The wings are marked with a dash and a taupe shade, while the hindwing displays a scalloped, light gray pattern. The moth can be characterized by the following features:

  • Gray, brown, and black colors
  • Furry and hairy body
  • Wingspan: 3.5 to 4.5 inches
  • Dash and taupe markings
  • Scalloped, light gray hindwing

Distribution and Habitat

The Modest Sphinx Moth is mainly found in North America, widespread across the U.S. It can be found in various habitats, such as woodlands and suburban areas. The moth is known to be nocturnal, flying and feeding mostly during the night.

Life Cycle and Development

Eggs

The modest sphinx moth begins its life as tiny eggs laid by the female moths on host trees such as willow, cottonwood, and poplar1. These eggs are:

  • Small and round
  • Dispersed singly or in small groups on host plant leaves

Larvae and Caterpillars

Once the eggs hatch, bright green caterpillars emerge, which are known as larvae1. Key features of modest sphinx moth larvae include:

  • A white, horn-like structure on their back-end
  • Yellow diagonal lines running along their body
  • Changing color from green to brown as they mature

The larvae feed on the leaves of their host plants, making them important pollinators1. They transform and grow over time, preparing for their next life stage.

Pupation and Adult Emergence

As larvae mature, they pupate in underground burrows or near the soil surface12. Modest sphinx moth pupation:

  • Can last for two weeks in summer
  • Often overwinters, with adults emerging in spring

Adult moths have distinctive forewings and hindwings, with a thin white line running through them1. These moths:

  • Are strong fliers
  • Feed on nectar from various flowers
  • Are also known as hawk moths

Comparison of Modest Sphinx Moth and Five-Spotted Hawk Moth

Aspect Modest Sphinx Moth Five-Spotted Hawk Moth
Caterpillar Color Green to Brown Green
Caterpillar Markings Yellow lines White V-shape
Host Plants Willow, Cottonwood, Poplar Tomato, Tobacco
Adult Moth Size 2.75 inches 3-4 inches
Distribution Canada, Texas, Florida, California Widespread in North America

Behavior and Ecology

Feeding Habits

The Modest Sphinx Moth (Pachysphinx modesta), like other sphinx moths, feeds on nectar using its long proboscis. They mainly feed in the evening or at night when flowers release more scent to attract pollinators. A few examples of plants they feed on are:

  • Big Poplar
  • New Mexico Thistle

Mating and Reproduction

Mating in Modest Sphinx Moths occurs during specific seasons. Males and females can be distinguished by:

  • Males: narrower wings and thinner abdomens
  • Females: broader wings and larger abdomens

After mating, the female lays eggs on the host plant, providing food for the emerging caterpillars.

Predators and Survival Strategies

Modest Sphinx Moths have developed various survival strategies against predators such as:

  • Camouflage: their wing patterns and colors help them blend into their surroundings.
  • Rapid escape: they quickly take off when threatened.

Some common predators of Modest Sphinx Moths include:

  • Bats
  • Birds

Comparison Table of Sphinx Moths and Butterflies

Feature Sphinx Moths Butterflies
Active during Night Day
Proboscis Long and coiled Long and coiled
Resting wing position Spread out or at an angle Folded together vertically
Antennae Tapered or feathery Club-shaped
Family within Lepidoptera Family Sphingidae Family Papilionoidea

Modest Sphinx Moths have a wide range, from the United States to Mexico. They inhabit various ecosystems, like forests, woodlands, and grasslands. Their wingspan measures between 110-140 mm, making them a large moth within the Sphingidae family.

Footnotes

  1. (https://mdc.mo.gov/discover-nature/field-guide/sphinx-moths-hawk-moths) 2 3 4 5

  2. (https://animals.mom.com/life-cycle-sphinx-moth-3991.html)

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 – Two Sphinxes from Canada: Modest Sphinx and Blinded Sphinx

 

amazing moths
Hey Bugman!
My son and I found these beauties at Moose Lake in south-eastern Manitoba, Canada and took these at about 11:30 p.m. June 25th. They were both of similar size, but we didn’t think to measure or estimate. We were too excited! What are they?
Laurell

Modest Sphinx Blinded Sphinx


Hi Laurell,
Letters like yours are causing us to mentally curse at our internet provider, Earthlink. Since being downgraded to dialup, the time spent answering just one letter has multiplied significantly. We downloaded your first 1.8M image, and it took about 15 minutes. It is a Modest Sphinx, Pachysphinx modesta, also sometimes called the Big Poplar Sphinx. The Big Poplar Sphinx is also the common name for a closely related species, Pachysphinx occidentalis. We are still waiting to see what your other moth might be. Your second Sphinx is a Blinded Sphinx, Paonias excaecatus.

Letter 2 – Modest Sphinx

 

Large Moth – Possibly Giant Silkworm?
Hi, i took this photo in our front garden earlier – there was also a female in our back garden but i couldnt get a photo. I would love to know what it is, but all the references ive seen have the wings the other way round… Anyway, hope you can identify it. Thanks
Andrew

Hi Andrew,
The Modest Sphinx, depicted in your photo, is sometimes called the Big Poplar Sphinx, but that common name also refers to another species.

Letter 3 – Modest Sphinx

 

The biggest moth I’ve ever seen
This moth looks similar to others on your site but not quite. It was hanging on our door in Lansing, Michigan a few weeks ago. When it flew away it looked like a small bird. What kind is it? I have a higher res pic if you need it.
William

Hi William,
Pachysphinx modesta is sometimes called the Modest Sphinx. Other writers call it the Poplar Sphinx.

Letter 4 – Modest Sphinx

 

unknown Nova Scotia Moth
Snapped these in Nova Scotia. Any ideas?

Dude,
What an awesome photo of a Modest Sphinx, Pachysphinx modesta.

Letter 5 – Modest Sphinx

 

large unknown sphinx moth–smerinthus??
Hi!
This beautiful-and very large moth appeared on the door of our camp in the Upper Peninsula of Michigan in May 2007. Any ideas? Thanks!
Angie Lucas

Hi Angie,
This is a Modest Sphinx, Pachysphinx modesta.

Letter 6 – Modest Sphinx

 

Subject: Moth?
Location: Tunbridge
July 14, 2012 5:42 pm
0800 7/14/12
Tunbridge vt
Signature: Powder

Modest Sphinx

Hi Powder,
This Modest Sphinx,
Pachysphinx modesta, is a female based on the turkey baster shaped abdomen.  That and other bits of information on the Modest Sphinx can be found on Sphingidae of the Americas.

Letter 7 – Modest Sphinx

 

Subject: Polyphemus Moth
Location: NE Ohio
October 27, 2013 2:54 pm
I think this is a Polyphemus Moth? If not, I would really like to know!
Signature: Ed

Modest Sphinx
Modest Sphinx

Hi Ed,
This is not a Polyphemus Moth.  It is a Modest Sphinx or Poplar Sphinx,
Pachysphinx modesta, and this sighting seems quite late in the year.  You can find more information on the Modest Sphinx on the Sphingidae of the Americas website.  We will be postdating your submission to go live during our absence from the office in early November.

Thank you very much for your identification. The pictures were actually taken ‎Friday, ‎July ‎29, ‎2011. I have been meaning to post them, but I am sure that you understand what time constraints can lead to! I don’t remember if I uploaded all 3 pictures that I took, so I will include them with this reply. Feel free to use them as you wish, just a minor acknowledgment would be appreciated. Thank you again for your time.
Edward Grether

Thank you Edward.  The photos were so similar that we felt we only needed to post the best with a bit of color correction.

Letter 8 – Modest Sphinx

 

Subject: Giant Moth!
Location: Holbein, Saskatchewan
June 11, 2015 11:20 pm
I have lived in Holbein Saskatchewan for the past 6 years. The last two spring/summers I have come across 2 of these giant moths which are about 3 inches long (we have an acreage consisting of 10 acres). I am from Vancouver and never have a seen such a huge moth. It’s quite stormy and windy out (probably about 15 degrees Celsius) and the moth was banging on the door (literally … I had to get up and check it out). It seemed to be attracted to light and the bright white door.
Signature: Kelly

Modest Sphinx
Modest Sphinx

Dear Kelly,
This impressive moth is a Modest Sphinx,
Pachysphinx modesta, and you can compare your image to this image on BugGuide.

Letter 9 – Modest Sphinx

 

Subject: What exactly is this type of moth
Location: Mason City Iowa
June 18, 2017 5:41 pm
This was in a city park hanging out at the base of the shelter pillar. It was not fond of moving about and needed about a 100 ft runway to get going to fly away. The moth just crawled onto my hand when I put in front of it. It was about 70 degrees in nornthern Iowa at about 5pm with a lightly wooded area as well as nature trails and farm land. The park is on the edge of tow .
Signature: Jarid

Modest Sphinx

Dear Jarid,
You can verify our identification of this Modest Sphinx or Poplar Sphinx,
Pachysphinx modesta, with images posted to the Sphingidae of the Americas site.

Letter 10 – Big Poplar Sphinx or Modest Sphinx???

 

Subject: Moth
Location: Bend Oregon
July 13, 2017 1:03 pm
Found this giant outside my apartment this morning. Thinking it may be a hawk moth, but not sure.
Signature: Ashley N

Big Poplar Sphinx or Modest Sphinx

Dear Ashley,
Based on images on the Sphingidae of the Americas site, we believe this is a Big Poplar Sphinx,
Pachysphinx occidentalis, one of the Hawkmoths, but since their ranges overlap in Oregon, we would not rule out that this might be the Modest Sphinx, Pachysphinx modesta, which is also pictured on Sphingidae of the Americas.

Letter 11 – Modest Sphinx

 

Subject: Sphix Moth
Location: Northern Wisconsin
July 20, 2017 10:33 am
I photographed this moth in late July (July 19) in Vilas County Wisconsin (northern WI). It looks like a Big Poplar Moth, but it’s coloring is not quite right. Can you help identify it?
Signature: Julie Draves

Modest Sphinx

Dear Julie,
We verified the identity of your Modest Sphinx,
Pachysphinx modesta, on Sphingidae of the Americas.  It is also commonly called the Poplar Sphinx.  A similar looking, related species in the same genus, Pachysphinx occidentalis, is commonly called the Big Poplar Sphinx, but it is a western species not reported in Wisconsin according to Sphingidae of the Americas.

 

Letter 12 – Recently Emerged Modest Sphinx

 

Subject:  What kind of moth is this?
Geographic location of the bug:  Upstate New York
Date: 06/09/2019
Time: 12:32 PM EDT
Your letter to the bugman:  A neighbor found this moth in her garden. It sprays a liquid from its hind end when threatened. We are in Bloomingdale, NY. Upstate. Wondering what kind of moth it is.
How you want your letter signed:  Al Schrage

Modest Sphinx

Dear Al,
This is a Modest Sphinx,
Pachysphinx modesta, and we speculate that the “liquid from its hind end” is a byproduct of its recent metamorphosis into an adult.  You can read more about the Modest Sphinx on Sphingidae of the Americas.

Letter 13 – Modest Sphinx Caterpillar

 

Subject:  Large green caterpillar
Geographic location of the bug:  Bangor ME
Date: 09/19/2019
Time: 06:53 PM EDT
Your letter to the bugman:  Found this caterpillar walking across the driveway toward the grass.  Having trouble identifying it.  Would appreciate your help.
How you want your letter signed:  PH

Modest Sphinx Caterpillar

Dear PH,
This is the caterpillar of a Modest Sphinx or Poplar Sphinx,
Pachysphinx modesta, and we identified on Sphingidae of the Americas where it states:  ”  These hornworms feed upon poplar, willow, and cottonwood, are very strong and develop to quite a size.  Larvae progress very rapidly on poplar. The green of the early hornworm instars is very much like the top of the poplar leaf while the pale green of the final instar more closely resembles the color of the underside of poplar leaves.  Larvae are extremely strong with powerful mandibles.”  The caudal horn on the Modest Sphinx Caterpillar is quite insignificant compared to the horns of other caterpillars in the family.

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    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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