Giant Silkworm Moth: All You Need to Know in a Nutshell

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The giant silkworm moth, a fascinating member of the Saturniidae family, captures the attention of many with its unique characteristics. These moths, ranging from medium to very large in size, possess stout, hairy bodies and feathery antennae, while female antennae can take the form of either a thin filament or a feathery structure source.

As a general overview, adult giant silkworm moths have a relatively short lifespan, only a few weeks, since their mouthparts are either small or completely absent, preventing them from feeding source. No wonder these beautiful insects are so captivating, with bright colors and eye-catching eyespots adorning the wings of some Saturniidae species source.

Giant Silkworm Moth Overview

Classification and Description

Giant silkworm moths belong to the family Saturniidae and are also known as saturniid moths. These moths are commonly found in North America and are known for their:

  • Large size
  • Hairy, stubby bodies
  • Feathery antennae

Family Saturniidae

The Saturniidae family includes a variety of moths, with some of the most notable species being:

  • Luna moth
  • Polyphemus moth
  • Promethea moth
  • Royal moths
  • Io moth
  • Cecropia moth
  • Imperial moth
  • Royal walnut moth
  • Regal moth

Notable Species

Here’s a brief comparison of a few notable giant silkworm moth species:

Species Size Color Other Characteristics
Luna Moth 4-6 inches Lime green Long tails on wings, translucent eyespots
Polyphemus Moth 4-6 inches Brown Large eyespots on wings, reddish-pink stripes
Cecropia Moth Up to 7 inches Reddish-brown Prominent, crescent-shaped eyespots, feathery antennae
Promethea Moth 2.5-4 inches Reddish-brown Smaller than Cecropia, eye spot near wing tip

These giant silkworm moths have a short adult life span, typically living for only a few weeks without feeding due to their small or absent mouthparts. Their large size, vivid colors, and unique appearances make them an interesting subject for the study and appreciation of North American moth species.

Life Cycle and Development

Egg to Caterpillar

In the life cycle of a giant silkworm moth, the first stage is the egg stage. The female moth lays her eggs and they develop into caterpillars. The eggs hatch after a certain period, depending on the species and environmental conditions.

  • Eggs can vary in color and shape
  • Hatching time varies among species

The Caterpillar Stage

Once the eggs hatch, they transform into caterpillars. These caterpillars have unique features that set them apart from other insect larvae.

  • Caterpillars possess spines for defense
  • They grow through a series of shedding and molting

Caterpillars primarily feed on a variety of host plants. Their diet contributes to their growth and development.

The Cocoon and Pupal Stage

When caterpillars reach a certain size, they enter the pupal stage and construct a cocoon. This is where metamorphosis occurs, transforming the caterpillar into an adult moth. The cocoon stage can vary in length and often involves overwintering.

  • Cocoon material varies with species
  • Metamorphosis duration depends on environmental factors

Adult Moths

Giant silkworm moths emerge as fully grown adults, fully developed with antennae and wings. Males and females have specific characteristics and roles within the species.

Male Moths:

  • Typically, larger antennae for detecting female pheromones
  • Males are often more vibrant in coloration

Female Moths:

  • Larger body size for egg production
  • Less vibrant coloration, often for camouflage purposes

Here’s a comparison table of the development stages:

Stage Characteristics Duration, Egg Duration, Caterpillar Duration,Cocoon & Pupa
Egg Varies in color and shape Varies
Caterpillar Spines for defense, feeds on host plants Varies
Cocoon & Pupal Cocoon material differs, involves metamorphosis and overwintering Varies
Adult Moth (Male) Larger antennae, vibrant coloration
Adult Moth (Female) Larger body size, less vibrant coloration

Understanding a giant silkworm moth’s life cycle and development stages helps in appreciating its importance in the entomology world. This knowledge is fundamental for anyone studying or working with these fascinating members of the Lepidoptera order.

Moth and Caterpillar Features

Giant Silkworm Moth Wings

Giant silkworm moths, belonging to the family Saturniidae, are known for their medium to large-sized, spectacular wings. They exhibit various colors and patterns, contributing to their striking appearance.

Caterpillar Morphology

Caterpillars of the giant silkworm moth family tend to be large and often have interesting features such as:

  • Tubercles: Small, rounded projections on their body
  • Spines: Sharp bristles for protection

For example, the cecropia moth is the largest moth in North America and exhibits these features.

Eyespots and Bright Colors

Many giant silkworm moths and their caterpillars display eyespots and bright colors on their wings and bodies. These features serve to:

  • Deter predators by mimicking larger animals
  • Signal their unpalatability or toxicity

The Imperial moth is a large, mostly yellow moth with spots, lines, and splotches of light to dark brown.

Defensive Features

Giant silkworm moth caterpillars possess defensive features, including:

  • Venom: Some species like the Lonomia obliqua caterpillar have venomous bristles that can cause symptoms ranging from mild discomfort to severe systemic bleeding in humans.
  • Glands: In some cases, caterpillars may release noxious chemicals or irritants as a defense mechanism.
  • Defoliation: Caterpillars of this family can cause significant defoliation of their host trees.

Comparison Table:

Feature Function Examples
Eyespots Deter predators; mimic larger animals Imperial moth, polyphemus moth
Bright colors Signal unpalatability; toxicity Imperial moth, luna moth
Tubercles Morphological feature Cecropia moth caterpillar
Spines Physical protection; deter predators Buck moth caterpillar
Venom Deter predators; harmful to potential threats Lonomia obliqua caterpillar
Glands Release noxious chemicals; irritants Io moth caterpillar
Defoliation Impact on host trees Various giant silkworm moth species

Habitat and Feeding

Host Plants

Giant silkworm moth caterpillars feed on various host plants. Some common host plants include:

  • Pine
  • Maple
  • Willow
  • Sassafras
  • Plum
  • Oak
  • Ash
  • Hickory
  • Sweet gum

These plants provide the nutrition necessary for the caterpillars to grow and develop.

Preferred Trees and Shrubs

Certain caterpillar species have specific tree and shrub preferences. For example, the hickory horned devil caterpillar, which turns into the royal walnut moth, mainly feeds on hickory and sweet gum trees but can also consume sumac, lilac, persimmon, ash, and beech trees ^(source).

Feeding Behavior

Giant silkworm moth caterpillars display particular feeding behaviors:

  • They mainly feed on tree foliage.
  • Some species may strip entire branches of their leaves.
Caterpillar Species Preferred Trees and Shrubs
Hickory Horned Devil Hickory, Sweet gum, Sumac, Lilac, Persimmon, Ash, Beech

In summary, giant silkworm moth caterpillars have diverse host plant preferences and feeding behaviors. Their habitat mainly consists of trees and shrubs that provide the necessary foliage for their growth and development.

Geographical Distribution

North American Populations

Giant silkworm moths, belonging to the Saturniidae family, can be found in various regions across North America. One example is the Cecropia moth, which is the largest moth in North America. These moths tend to reside in forested areas.

Giant Silkworm Moths Around the World


The Lonomia obliqua, a specific species of giant silkworm moth, is found in Brazil. The larval form of this moth is known for its toxicity, causing numerous poisonings and human fatalities yearly.


Giant silkworm moths are less common in Europe than in other regions, but exist nonetheless. Specific species might be found in certain European countries, such as the Giant Peacock moth, which lives in Mediterranean countries.


Here is a brief comparison table of Giant Silkworm Moth geographical distribution:

Region Species Traits Remarks
North America Cecropia moth Largest moth in North America Forest dwellers
Brazil Lonomia obliqua Toxic larval stage Causes numerous poisonings and fatalities
Europe Giant Peacock moth Eye-catching colors and patterns Found in Mediterranean countries

In conclusion, giant silkworm moths can be found in various regions across the globe, with species characteristics and distribution depending on local ecosystems and habitats.

Research and Resources

University of Kentucky Entomology Department

The University of Kentucky Entomology Department provides valuable information on giant silkworm moths, including their appearance, habitat, and life cycle. For instance, they discuss the differences between male and female moths in terms of size, color, and antennae. Some key features include:

  • Males: smaller with feathery antennae
  • Females: larger with a thin filament or feathery antennae

Examples of giant silkworm moths found in North America are the Annelaea Polyphemus, Callosamia Promethea, and Actias Luna.

The Wild Silk Moths of North America

In the book The Wild Silk Moths of North America, you can learn more about the diverse giant silkworm moth species inhabiting the continent. Some fascinating aspects of these moths include:

  • Large size
  • Striking colors
  • Unique patterns

Comparison of three North American giant silkworm moths:

Species Size Colors Special Features
Annelaea polyphemus Medium Brown shades Prominent eyespots
Callosamia promethea Medium to large Dark shades with wavy patterns Variable color pattern
Actias luna Large Light green with long tails Crescent-shaped eyespots

Remember, the information provided by these resources is for educational purposes and can help you better understand and appreciate the world of giant silkworm moths.

Threats and Conservation

Poison and Predators

The Giant Silkworm Moth (Lonomia obliqua) is a large moth belonging to the Saturniidae family and is known for its toxic effects. Despite its name, the danger lies within its caterpillar stage. The larval form of the L. obliqua can be deadly and has caused several human deaths every year.

Characteristics of the venomous caterpillar include:

  • Hemorrhagic venom
  • Gregarious behavior
  • A potential risk for human contact

The major predators for these caterpillars are birds, ants, and wasps. However, their gregarious behavior and venom help protect them from these threats.

Human Impact

Giant silk moths face various threats from human activities. These threats include:

  • Deforestation and habitat loss
  • Pesticides and chemical exposure
  • Exotic and invasive species competition
Threat Impact
Deforestation Loss of host plants for larvae and nectar plants for adults
Pesticides Poisonous pesticides negatively affect moths’ survival and reproduction
Invasive Species Invasive species compete with silk moths for resources, leading to a decline in moth populations

To conserve giant silk moths, efforts can be made towards habitat preservation, limiting the use of pesticides, and controlling invasive species. Individuals can contribute by planting host and nectar plants in their gardens to support the moths’ life cycle.

Reader Emails

Over the years, our website, 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 – Caterpillar from Guatemala


Subject:  Caterpillar
Geographic location of the bug:  Antigua Guatemala
Date: 10/21/2018
Time: 03:35 PM EDT
Your letter to the bugman:  Hello,
I found these caterpillars in my garden in Antigua Guatemala in July.
I made some research and it could be a Costa Rican hairy caterpillar (Automeris metzli ?) but I am not sure as Antigua is located at 1600 m in the mountains…
What do you think ?
Thank you !
How you want your letter signed:  Voiz

Automeris Caterpillar

Dear Voiz,
We believe you have the genus
Automeris correct, but we are not certain of the species.  It looks to us like it might be Automeris boucardi, but we will check with Bill Oehlke to see if he can verify the species identity.

Letter 2 – Caterpillar from Tanzania


Subject: unknown caterpillar
Location: Africa – Tanzania
March 18, 2013 2:02 am
hello all,
a friend found this large and beautiful caterpillar on a tree in tanzania, i think i could be an Imbrasia species, but i couldn´t find the exact species. Perhaps you can help me.
Thank you very much… greetings from Germany !
Signature: –


This really is a beautiful caterpillar.  We will contact Bill Oehlke to get assistance with its identification.

Letter 3 – Caterpillars


My son came in with a huge green caterpillar with big orange horns last night. It was probably 5-6 inches long and 3/4 inch thick. It extended across his hand. Looked like one of those chinese dragons.
He had been out in his jeep earlier and thought some how it had gotten in the car, for later when he was standing by the car, it crawled across his foot. We have never seen anything like it. Do you have any ideas?
Thank you, J.Hansel

Dear J.
It is the caterpillar of the Royal Walnut Moth,Citheronia regalis, which has the largest caterpillar in North America. The caterpillar, which your son found goes by the common name of Hickory Horned Devil. Please send a photo, we would love to have it. The moth is also quite beautiful. It has olive colored upper wings with red veins and yellow spots, orange red hind wings with yellow spots, and a reddish body with yellow bands.

Thank you for the quick answer. We took it to the zoo and found out you are correct. Such a thrill to see it. A couple of years ago I had a similar thrill I could share with the grandchildren. I captured a huge moth that was a big as my husbands hand. It was a soft tan color with pink designs in the wings. When I let it fly it looked like a bird going over the house. I remember looking it up but I forgot what I found . I feel the Lord truly blesses us when we see these things up close in their own environment. You know that you will never have the same experience again. Thank you for your help, Judy Hansel
P.S. I did get pictures with my new digital camera. When I learn how to send it I will send you the picture.

I’m glad we could be helpful Judy,
Don’t forget to send the photos when you have a chance. We would love to post one with your letter. The moth you found years ago is a member of the family Saturnidae, the giant silk moths. Based on your color description, I would guess probably an Ailanthus Silk Moth, though it could also be a Cecropia.


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    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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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5 Comments. Leave new

  • Julian Donahue
    March 18, 2013 4:38 pm

    I think your contributor is on the right track. His larva looks similar to the “Mopane Worm” (Gonimbrasia belina; Saturniidae)) I photographed on mopane (Colophospermum mopane; Fabaceae) at the Hobatere Lodge, Damaralanbd, Namibia, 26 March 2010. The larvae are collected, dried, and highly prized as food (tried one, but too “spiky” for me to really enjoy). [Don’t see how to post a photo in my comment, so I’ll try submitting it separately.]

    • Thanks Julian,
      We are awaiting an identification request on this from Bill Oehlke who runs the World’s Largest Saturniidae Site. We will post your photo immediately.

  • Can anyone tell me what kind of caterpillar this is? It’s about 4″ long and 3/4″ in diameter.

  • I don’t know how to post a picture, but it has horns on its head, white dots down the side, and is reddish on the top, greenish on the bottom, with sparse hair!


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