The Transformation of Hornworms: Discover What They Become

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What Do Hornworms Turn Into

Do hornworms turn into butterflies? What do hornworms turn into? We look at answers to these questions in the article below.

There are many types of Hornworms, but the most common moths found in gardens are tomato and tobacco hornworms. Hornworms are also known as hawk moths or hummingbird moths. 

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The female moths lay eggs on leaves that hatch to produce larvae or caterpillars. The caterpillar turns into pupae which in turn transform into moths with beautiful wings. Hornworms are nothing but the caterpillar stage of hawk moths.

What Do Hornworms Turn Into

 

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Do Hornworms Turn Into Hummingbird Moths?

Yes, after the pupa stage, hornworms transform into hummingbird moths. From a distance, these moths look very similar to tiny hummingbirds, which is why the insects are called “hummingbird moths.” 

One of the reasons behind their name is their long proboscis, through which they suck in nectar from flowers. This proboscis can be as long as 14 inches. 

When these large insects hover near the flowers, their proboscis looks similar to hummingbirds’ beak from a distant place. 

Hornworm caterpillars are also known as sphinx worms due to the way they sit on leaves. They raise their head like a sphinx when they get startled or feel threatened.

Do Hornworms Turn Into Butterflies?

Hornworms follow a similar life cycle as butterflies, but they aren’t butterflies! They turn into winged moths, and their wings have beautiful designs on them. 

From a distance, you might mistake a hornworm moth for a butterfly. But the two species of insects are entirely different, and it’s just a misconception that Hornworms turn into butterflies.

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What Do Tomato Hornworms Turn Into?

Tomato hornworms turn into large moths with colorful wings, about two to eight inches wide. The colors can be anything from golden to brown to grey and even pink.

Tomato hornworms are one of the largest caterpillars in the world. These pests are notorious for eating tomato plants and other crops of the nightshade family, including eggplants, tuber, and pepper. 

Female moths lay eggs on the underside of leaves. These eggs hatch and transform into inches-long caterpillars in around three to four weeks. They continue to grow bigger and longer, feasting on leaves until they reach a length of about 4 inches.

Then the caterpillars leave the plants and fall down into the soil. The moths emerge out of the pupae after two to three weeks. After coming out as moths, they prepare for reproduction and producing the next generation.

What Do Hornworms Turn Into

 

What Do Green Hornworms Turn Into?

There are two common types of hornworms: Tomato hornworms (Manduca quinquemaculata) and tobacco hornworms (Manduca sexta). Both worm species are green in color in their caterpillar stage but transform into moths of different colors. 

The key difference, as the name suggests, is that tobacco hornworms prefer to feast on the leaves of the tobacco plant.

Like tomato hornworms, tobacco hornworms also pupate on the surface of the soil around tobacco plants. Tobacco moths emerge out of the pupae during May and June. 

Tobacco moths have gray-colored wings, and the upper end is grayish brown. They also have two light bands on each forewing. The wingspan of the tobacco moth is much smaller: it is only about 5/8th of an inch wide.

Once they emerge out of the pupae, they turn into moths and mate to reproduce further generations of the hornworms. 

What Do Blue Hornworms Turn Into?

Like green hornworms, blue hornworms also turn into moths because they are one and the same! The difference in color is because of what they are eating. Green hornworms can even be transformed into blue ones by changing their diet. 

For those who are a bit scientifically minded, green hornworms are green because two pigments in their bodies combine to give them this color.

Hemocyanin is a blue pigment that is the equivalent of hemoglobin present in humans. Xanthophyll is a yellow toxin produced when they eat the leaves of nightshade plants like tomatoes or tobacco. And as any artist knows, blue and yellow combine to make green!

So, when these insects eat a diet that does not contain tomato, tobacco, or any vegetable of the Solanaceae family, they don’t get the yellow component that makes their characteristic green color. 

As an aside, the color green is a natural way to camouflage themselves in the wild; it is not by accident that they turn green. 

What Do Hornworms Turn Into

 

How Long Does It Take for a Hornworm to Pupate?

The life cycle of a hornworm has four major stages:

Egg

After mating, the female moth lays eggs under the leaves. The eggs are small, smooth, and green. The eggs are laid on the leaves of plants of the nightshade family and usually take three days to hatch. 

Larva (Caterpillar)

Once the egg gets hatched, the hornworm caterpillars stay on the same leaf and feed on them to grow into a larger form known as instars. This is their larval stage. 

Throughout their growth, they keep moving across their host plant, eating different parts to survive. This is an adaptive strategy that helps avoid wasting energy in finding a reliable source of food. They grow till they are about 4 to 5 inches long.

After 3 to 4 weeks of growing, they drop off leaves and move to the next stage of the lifecycle. 

Pupa

The hornworms drop to the soil and burrow in it to transform into pupae. The caterpillars are dark green, while the pupae are deep reddish-brown. 

Hornworms remain inside the soil in the form of pupae for about two weeks and remain there until they are grown to emerge out of the pupa as adult moths. 

Adult

Adult moths emerge pupae with beautifully patterned wings that suck nectar from flowers. The adult life of the moths is spent on mating and reproduction. 

What Do Hornworms Turn Into

 

Frequently Asked Questions 

How long does it take a hornworm to turn into a moth?

The caterpillar form of a hornworm becomes fully grown in about three to four weeks. Then they drop off to soil from the plant leaves and become pupae. 

They remain as pupae for two weeks until they emerge as adult moths. So, hornworms take approximately five to seven weeks to grow into adult forms. 

Can you keep a hornworm as a pet?

Hornworms are usually not kept as pets. People use them as feeders for reptile pets. You can raise hornworms for feeding at home by following a proper diet to avoid toxin synthesis in their bodies. You also need to make sure you provide proper sunlight and optimum temperature.

Can hornworms hurt you?

Hornworms are harmless to humans other than being greedy pests of tomato plants. Hornworms do not bite or sting humans, so they cannot harm you. Their horns are weak and harmless too.

What animal eats hornworms?

Most reptiles feed on hornworms, such as bearded dragons, leopard geckos, and Uromastyx. Some amphibians and arthropods (insects), such as tarantulas and scorpions, feed on the worms.  

Wrap Up

Hornworms transform into moths by starting as eggs, turning into caterpillars, pupae, and finally, adult moths. The entire journey from egg to moth is fascinating. It is interesting to note the various adaptations these bugs have taken to avoid getting eaten by predators.

Thank you for reading!

Reader Emails

Over the years, our readers have sent us several emails on this topic. Please go through them below.

Letter 1 – Hornworm metamorphoses into Silver Striped Hawkmoth in South Africa

Subject: Caterpillar mystery answered
Location: Johannesburg, South Africa
May 8, 2013 12:56 am
Hi there
I while ago I asked about a caterpillar that I found. For the life of me I could not find out what it was, but was convinced it would turn into some kind of hawk/sphinx moth.
Luckily a few days later it started to pupate and I figured I would just wait and see what it would turn into. I finally have my answer.
This gorgeous little critter is a silver striped (aka vine) hawk moth – and he is beautiful!
I have been blessed to find 6 different hawk/sphinx moth species in my garden (johannesburg, south africa) and can now add this little guy to my sightings.
So excited 🙂
Signature: Bug lover – Cait Beling

Silver Striped Hawkmoth Caterpillar
Silver Striped Hawkmoth Caterpillar

Dear Cait,
We are terribly sorry if you submitted your identification of the Hornworm to us and we did not respond.  We have a very tiny staff.  Thanks so much for including photos of two stages of the life cycle of the South African Silver Striped Hawkmoth,
Hippotion celerio.  More information on the Silver Striped Hawkmoth can be found on the Sphingidae of the Eastern Palaearctic website.  Also, congratulations on your successful rearing of the adult moth.  Did you get to witness any of the eclosion process?  Do you have a photo of the pupa to include in the posting?

Silver Striped Hawkmoth
Silver Striped Hawkmoth

Letter 2 – Possibly Banded Sphinx Caterpillar

Subject: caterpillar
Location: Northwest Houston, TX
October 24, 2014 5:51 am
I found this in a parking lot in Houston, TX. I’ve lived here all my life and have never seen anything like it. It looks like some of the Sphinx Moth caterpillars I’ve seen in Google Image Search, but it doesn’t quite match any of them. Could you help me identify it?
Signature: Jeremy

Hornworm
Hornworm may be Banded Sphinx

Hi Jeremy,
We agree that this is a Hornworm in the family Sphingidae, even though it appears to be lacking a horn.  Our first impulse was that this resembles a pre-pupal Waved Sphinx Caterpillar, but the lack of a horn and the orientation of the light slashes behind the spiracles and running from front to back in orientation would eliminate that as a correct identification.
  A prepupal Modest Sphinx Caterpillar pictured on Sphingidae of the Americas also has the white slash marks oriented the opposite direction.  As we must leave for work now, we are going to write to Bill Oehlke to get his assistance.  We wonder if it might be an unusually colored Ficus Sphinx, Pachylia ficus.  We were unable to locate its identity on the Sphingidae of the Americas Texas page.

Wow, thanks!  I honestly didn’t expect such a quick response. You guys rock! Let me know what Bill thinks.

Letter 3 – Hornworm

Subject: It’s something new for you guys – a bug!!
Location: Yarmouth, ME
September 5, 2016 10:43 am
Hello!
Found this bug hanging out in our lawn, not on any plants, kinda maybe even trying to burrow? Not sure because my dog bothered it until it stopped trying to move 🙁
At that point, I moved it to the garden, tried and failed to research it, and then went back and took the attached photos.
Anyway, any help identifying this guy would be super appreciated!
Signature: Mikala

Waved Sphinx Hornworm
Waved Sphinx Hornworm

Dear Mikala,
Using the Sphingidae of the Americas site, we quickly identified your Hornworm as that of a Waved Sphinx,
Ceratomia undulosa.  According to the site:  “In the fifth instar, the spiracular ovals are decidedly red and the anal horn is off-white to pinkish laterally”  and “Just prior to pupation, larvae frequently take on a rosy hue.”  Your individual was getting ready to dig underground to pupate.  We hope it was able to realize its mission.

So neat! I’ve lived here most of my life and I’ve never seen anything like it before. Thanks for your help!
Mikala

Letter 4 – Hornworm of the Aussie White-Brow Hawkmoth from Australia

Subject:  Australian Caterpillar
Geographic location of the bug:  Queensland, Australia
Date: 03/30/2018
Time: 09:04 PM EDT
Your letter to the bugman:  Found this large caterpillar on a vine bush just curious as to what it is
How you want your letter signed:  Anonymous

Hornworm: Gnathothlibus eras

Thanks to Butterfly House, we quickly identified this Hornworm as Gnathothlibus eras, the Aussie White-Brow Hawkmoth.  Butterfly House states:  “When disturbed, the caterpillar curls its head down onto its first two pairs of legs, and displays the third pair. The caterpillar can also exude liquid from its mouth, and has even been heard to give a squeal.”  Listed food plants include Grape vine and Sweet Potato Vine.

Hornworm: Gnathothlibus eras

Letter 5 – Hornworm from Australia: Psilogramma casuarinae

Subject:  Omg what is this and where did it come from
Geographic location of the bug:  Mittagong NSW  Australia
Date: 03/27/2018
Time: 08:12 PM EDT
Your letter to the bugman:  It’s the beginning of Autumn
Surrounded by privet trees
Several veggie gardens
Southern Highlands region of NSW
Nearly stepped on this thing at 4am in morning on my lounge room rug
Never seen anything like it
Realise it’s a grub of some kind
Put it in container
What should I do with it
Keep or let go
Will it damage my veggies
Does it turn into a butterfly or moth or something
Please help ASAP
Don’t want to leave it in container to die if it needs to finish it’s life cycle but don’t want it damaging my veggie gardens
How did it get here
No one I’ve asked had ever seen one before
My niece thinks it may be a type of horn worm
Please help
How you want your letter signed:  Freaked me out – sarah

Hornworm: Psilogramma casuarinae

Dear Sarah,
Your niece is correct.  This is a Hornworm, the caterpillar of a Hawkmoth in the family Sphingidae.  We identified it on Butterfly House as
Psilogramma casuarinae, a species with no common name, thanks to this additional image.  Butterfly House has a list of food plants including olive, privet and jasmine, and the site also indicates “The caterpillar grows to a length of about 8 cms. When the caterpillar is fully grown, it leaves the food plant and walks up to 20 metres to pupate under the soil.”  Because of the pink coloration, we are surmising that your individual is pre-pupal,  and we suspect it might have already begun to transform.  You can return it outside to an area where it can dig underground.  It will not continue to feed at this time and it will not eat your veggies.

Hornworm: Psilogramma casuarinae

Letter 6 – Hornworm from Belize is Isognathus scyron

Subject: Larva
Location: Southern Belize
January 17, 2014 7:38 pm
Moth or butterfly larva? Species?
Signature: Jerry Brown

Hornworm
Hornworm

Hi Jerry,
This is a Hornworm, a caterpillar in the moth family Sphingidae.  It appears to be a young instar.  Caterpillars undergo five distinct stages or instars, molting and transforming size and appearance after each.  The final molt after the fifth instar results in the pupa.  We will attempt to provide a species identification for you, and that will require clicking on each of the links on the Sphingidae of Belize page on Bizland.  Should you decide to undertake that task, please let us know if you find any matching images.  Unfortunately, each distinct instar isn’t pictured for every species.  Knowing the plant upon which it was feeding would be very helpful.

Update:  Isognathus scyron
Identification courtesy of Bostjan Dvorak:  Bostjan provided us with a name, and we have found some photo on BiodiversidadVirtual and on Cesar Crash’s Brazilian website Insetologia.

Thanks for the ID. Very cool. Web link does not list Belize, so maybe that is new info.
regards
Jerry

Hi Jerry,
We believe the Bizland documentation is based on actual sightings, and perhaps there has never been a verified sighting in Belize.  Bizland does report sightings in Costa Rica and Guatemala as well as South America and Cuba.

Letter 7 – Hornworm Metamorphosis

hornworm almost-pupa
Hi Bugman,
For all the pics I’ve sent you, nothng had ever been good/interesting enough (to you!) for inclusion. This time, we have something you don’t have yet. My 7yo and I were digging out our tomato plants yesterday, when he saw this in the dirt. It is a hornworm in the process of becoming a pupa, as far as I can tell. You can actually see his horn there at the bottom of the pic. His legs were still there too, and he squirmed a bit, but is clearly shorter and more, uh, pupa-shaped than the big fat guys we saw into December. His body markings were gone. We gently reburied him–we’re not planting tomatos there next year–but I don’t know if we did him in just by digging him up. This is from Westchester, CA.
Audrey and Tony

Hi Audrey and Tony,
You have tapped into our guilt. First, we heartily apologize for not ever posting your submissions. There are many possible reasons. Sheer volume is high on the list. If letters have no subject line, then we tend to just ignore them except on very slow days. Often people send letters and forget to attach images and we don’t have time to request that they resend. Who knows? At any rate, we are happy to get your latest sumbission. Reburying the Hornworm probably did not interfere with the metamorphosis. The next step is that the larval skin will split and the pupa will wriggle out.

Letter 8 – Tomato Hornworm or Tobacco Sphinx, newly metamorphosed


We were out visiting my parents last weekend in Central Pennsylvania and around dusk came across this insect. He seemed to be injured and was having problems moving around. He looked like an odd cross between a caterpillar, a grasshopper, and a butterfly. Looking through the other bugs posted on your site, we think it might be some sort of Sphinx, but it didn’t appear quite right. I took a bunch of pictures but these three turned out the best. Any help you can provide in identifying this bug would be appreciated.
Sincerely,
Bill Blankmeyer

Hi Bill,
This is a newly metamorphosed Manduca sexta, the Tomato Hornworm or Tobacco Sphinx. Soon its wings will be strong enough for flight, and they are very powerful fliers.

Authors

  • Bugman

    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 Dhir

    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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Tags: Hornworm metamorphosis, Hornworms, Hummingbird moths

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10 Comments. Leave new

  • Bostjan Dvorak
    January 24, 2014 12:16 pm

    Hello and nicest wishes for 2014!

    This is indeed a young instar of a hawkmoth larva, namely from the genus Isognathus; it seems to be an Isognathus scyron. This and related species pupate among foliage on the soil and build beautiful black pupae with orange markings; these develop into elegant greyish moths with yellowish or orange underwings. In Erinnyis, Pseudosphinx and Isognathus, the habitus is similar to that of the Sphinginae, but systematically, the three genera belong to the subfamily of the Macroglossinae. Many of the species live on Apocynaceae (Frangipani, Oleander …) and Euphorbiaceae, and their colorful caterpillars are often gregarious in their first instars.

    Best from Berlin,
    Bostjan

    Reply
  • Bostjan Dvorak
    January 24, 2014 12:16 pm

    Hello and nicest wishes for 2014!

    This is indeed a young instar of a hawkmoth larva, namely from the genus Isognathus; it seems to be an Isognathus scyron. This and related species pupate among foliage on the soil and build beautiful black pupae with orange markings; these develop into elegant greyish moths with yellowish or orange underwings. In Erinnyis, Pseudosphinx and Isognathus, the habitus is similar to that of the Sphinginae, but systematically, the three genera belong to the subfamily of the Macroglossinae. Many of the species live on Apocynaceae (Frangipani, Oleander …) and Euphorbiaceae, and their colorful caterpillars are often gregarious in their first instars.

    Best from Berlin,
    Bostjan

    Reply
  • Bostjan Dvorak
    October 25, 2014 4:09 pm

    Could it be an Eumorpha fasciatus caterpillar?
    Interestng photo of an unusual colour pattern (in prepupal stage).

    Nicest wishes from Berlin,
    Bostjan

    Reply
    • Hi Bostjan,
      Thanks for the help. We agree that the larva of a Banded Sphinx seems like a strong possibility, which explains both the lack of a caudal horn and the direction of the light slash marks.

      Reply
  • Hey. Mine has been in its cocoon stage for like 2-3 days. I was wondering how long does it usually take for them to hatch from the cocoon? I want to film it hatching.

    Reply
  • Lucy Leistner
    October 2, 2017 12:08 pm

    I live in Alabama in the USA. My daughter found the hornworm in our backyard. It looks just like your picture. How could it have gotten here?

    Reply
  • Hi, It’s Monday 27th April 2020 at about 4pm. I just found my cat playing with something that looked very similar to the Hornworm: Psilogramma casuarinae pictured above, only it was more green all over.
    I want to know if it’s poisonous for the cat to eat, as he was trying to pick it up in his mouth & kept jumping back whenever he tried to bite it. (It could just have been that the spike was poking him in the face ;-p )
    The caterpillar was doing big half-circle flips but then slowed down to almost no movement at all. I put it in a jar but it looks pretty dead.

    Reply

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