Cinnabar Moth Life Cycle: Discover the Fascinating Stages!

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The cinnabar moth is a fascinating species of moth that plays a crucial role in controlling the population of tansy ragwort, a plant that can be toxic to both humans and livestock. Found in various parts of the world, the life cycle of the cinnabar moth involves several stages, each with their unique characteristics.

Female cinnabar moths have the capacity to lay up to 300 eggs on the underside of ragwort leaves, usually in batches of 30 or 60. This is an important part of the moth’s life cycle, as it ensures the survival of the species and contributes to the natural regulation of tansy ragwort plants. After the caterpillars hatch, they begin to feed on the plant, eventually growing into adult moths ready to continue the cycle. By understanding the cinnabar moth’s life cycle, one can appreciate its significance in the ecosystem.

Cinnabar Moth Identification

Wingspan

The cinnabar moth has a wingspan ranging from 32-42 mm. This size makes them easily recognizable in comparison to other moths.

Forewings

Cinnabar moth forewings feature a unique pattern, with:

  • Bright pinkish-red stripes
  • Black bands

Hindwings

Hindwings of the cinnabar moth are also distinctive, with:

  • Dark black color
  • Pinkish-red patches at the bottom
  • Bright red border

Red and Black Wings

Cinnabar moths are known for their vibrant red and black wings. These colors serve as a warning to predators, indicating their toxicity.

Feature Cinnabar Moth Other Moths
Wingspan 32-42 mm Varies
Forewing Red stripes Varies
Hindwing Red patches Varies
Overall Color Red and black Varies

Body Length

The body length of a cinnabar moth ranges from 16-20 mm, giving them a compact appearance. This size is typical for moths within their family.

Cinnabar Moth Life Cycle

Eggs

Female cinnabar moths lay up to 300 eggs, typically in batches of 30 or 60 on the underside of ragwort leaves. Cinnabar moth eggs are:

  • Small, round and yellow
  • Laid on host plants like ragwort and groundsel

Caterpillars

Once hatched, caterpillars feed on the ragwort leaves in their immediate vicinity. Cinnabar caterpillars are known for:

  • Distinct black-and-yellow striping
  • Five larval stages, or instars
  • Feeding on toxic plants for self-protection from predators

Pupal Stage

After reaching full size, cinnabar caterpillars pupate to become adults. During the pupal stage, they:

  • Form a brownish cocoon
  • Undergo metamorphosis
  • Pupate for approximately 14 days

Adult Moths

The adult cinnabar moths emerge from their cocoons and begin their role in the life cycle. Adult moths display:

  • Bright red hindwings with black markings
  • Grayish-brown forewings
  • Short lifespan, typically 1-2 weeks

Comparison table: Cinnabar Moth Life Stages

Life Stage Duration Characteristics
Eggs Few days Yellow, laid on ragwort leaves
Caterpillars 2-3 weeks Striped, 5 instars, toxic due to diet
Pupal Stage 14 days Brownish cocoon, metamorphosis
Adult Moths 1-2 weeks Red and black wings, short lifespan, responsible for reproduction

Habitat and Distribution

Europe

In Europe, cinnabar moths are native and widely distributed, with their preferred habitat being open grasslands, heathlands, and areas with abundant ragwort plants. In the UK, they are commonly found in southern and central regions.

North America

Cinnabar moths were introduced to North America in the 1960s for biological control of the invasive tansy ragwort plant. They have now established populations in the Pacific Northwest, particularly in Oregon and Washington. Their preferred habitats include meadows, fields, and areas where tansy ragwort thrives.

Australia

Cinnabar moths have been introduced to Australia as a biological control agent for the ragwort plant, which is toxic to livestock. Populations have established in eastern parts of the country, predominantly in New South Wales and Victoria. They are found in open, grassy areas where their host plant, the ragwort, grows.

New Zealand

In New Zealand, cinnabar moths were also introduced as a biological control for ragwort. They have successfully established populations in various regions, mainly in the North Island. Their preferred habitats are pasturelands, roadsides, and wetlands where ragwort is present.

Asia

While there is less information about cinnabar moth distribution in Asia, native populations are known to exist in some regions, particularly in Central Asia. Habitat preferences likely mirror those in other regions, with a focus on areas supporting the growth of ragwort plants.

Comparison table of cinnabar moth distribution:

Region Native/Introduced Habitat Preferences
Europe Native Grasslands, heathlands, abundant ragwort
North America Introduced Meadows, fields, areas with tansy ragwort
Australia Introduced Open grassy areas, presence of ragwort
New Zealand Introduced Pasturelands, roadsides, wetlands with ragwort
Asia Native Unknown, likely similar to other regions

Host Plants and Feeding

Ragwort Plant

Cinnabar moths primarily depend on ragwort plants for feeding and reproduction. Ragwort includes species like common ragwort (Senecio jacobaea) and tansy ragwort (Senecio vulgaris). Females can lay up to 300 eggs, usually in batches of 30 or 60 on the underside of ragwort leaves. Newly hatched caterpillars feed on the surrounding areas of hatched eggs.

Other Plants

Besides ragwort, cinnabar moths sometimes feed on other plants from the same family, like groundsel (Senecio vulgaris). However, ragwort remains their primary host plant.

Nectar

Adult cinnabar moths feed on nectar from various flowers. Moths play a crucial role in nocturnal pollination, visiting flowers with pale or white petals and a strong fragrance. Some moths are also active during the day.

Host Plant Description Relation to Cinnabar Moth
Ragwort Tall, yellow-flowered plant from Senecio genus Primary host plant for feeding
Groundsel Smaller plant from Senecio genus; yellow flowers Secondary host plant for feeding
Nectar-rich flowers Flowers with pale or white petals and strong fragrance Food source for adult cinnabar moths

Key Features:

  • Primary host plant: Ragwort
  • Eggs laid on underside of ragwort leaves
  • Newly hatched caterpillars feed on leaves
  • Adult cinnabar moths feed on nectar

Characteristics of Host Plants:

  • Ragwort: Tall and yellow-flowered, primary host
  • Groundsel: Smaller and yellow-flowered, secondary host
  • Nectar-rich flowers: Pale or white petals, strong fragrance, visited by adults

Toxicity and Defense Mechanisms

Poisonous Larvae and Adult Moths

Cinnabar moth larvae are highly toxic, making them unappealing prey for predators. Adult moths, though not as toxic as the larvae, still possess chemical defenses to deter potential predators.

Toxic Larvae

  • Brightly colored caterpillars
  • Feed on toxic ragwort plant

Adult Moth Defenses

  • Warning coloration (red and black)
  • Retain some level of toxicity

Toxins

Cinnabar moth larvae accumulate toxins from the ragwort plants they feed on. These toxins, called pyrrolizidine alkaloids, protect the larvae from being consumed by predators such as birds or livestock.

Unpalatable to Predators

Due to their toxicity, cinnabar moth larvae and adult moths are unpalatable to many potential predators. Birds, in particular, learn to associate the larvae’s bright colors with their unpleasant taste and avoid them.

Examples of Unpalatable Predators:

  • Birds
  • Mammals (e.g., mice and squirrels)
Predators Cinnabar Moth Larvae Unpalatable Adult Cinnabar Moths Unpalatable
Birds
Mammals
Insects Some resistance Some resistance

In summary, the cinnabar moth has evolved effective defense mechanisms in both its larval and adult stages. These mechanisms include toxicity from ingesting toxins in their diet and bright warning coloration that helps deter predators such as birds and mammals.

Conservation and Management

Conservation Status

The cinnabar moth is not currently classified as an endangered species. However, its role in controlling tansy ragwort, a toxic weed, has earned it recognition as a beneficial insect.

Managing Ragwort

Landowners and gardeners can help manage ragwort populations by implementing several strategies:

  • Regularly inspect gardens and properties for the presence of ragwort
  • Manually remove young plants or use environmentally friendly herbicides to control its spread
  • Encourage the presence of cinnabar moths by providing suitable habitats

The cinnabar moth plays a crucial role in controlling ragwort. Female moths can lay up to 300 eggs on ragwort leaves, which the larvae consume upon hatching, ultimately suppressing the weed growth.

Impact on Native Plant Populations

Although cinnabar moths are mainly beneficial due to their role in controlling ragwort, it’s essential to be aware of their potential impact on native plant populations:

  • Cinnabar moth larvae prefer ragwort but may feed on other plants if necessary
  • Overpopulation of cinnabar moths may lead to unintended consequences on local ecosystems

While the pros of the cinnabar moth’s impact on managing ragwort are evident, it’s important to monitor and balance their populations to avoid any harm to native plants.

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 – Cinnabar Moth Caterpillar

 

Subject: HELP
Location: Oregon
July 26, 2014 10:48 am
We have a caterpillar that is going to turn into a cinnabar moth, we already know what bug it is but it just went into a cocoon (yay!). How long will it be in a cocoon?
Signature: Seriously bugged

Cinnabar Moth Caterpillar
Cinnabar Moth Caterpillar

Dear Seriously bugged,
According to Bug Life:  “Caterpillars are feeding from July – early September and are initially pale yellow but soon develop bright yellow and black stripes to deter predators. … The caterpillars overwinter as pupa in a cocoon under the ground. The adult moths emerge around mid May and are on the wing up until early August, during which time males and females will mate and eggs are laid.”
  If that is accurate, you will not experience eclosion until next spring.

Letter 2 – Cinnabar Moth Caterpillar

 

Subject:  Tyria jacobaeae moth caterpillar
Geographic location of the bug:  Silverdale, WA
Date: 07/14/2018
Time: 04:22 AM EDT
Your letter to the bugman:  I thought you might like a photo of a Tyria jacobaeae (Cinnabar) moth  caterpillar, a species introduced into North America to help keep it’s host plant, Tanacetum vulgare (Tansy ragwort- flower shown  in photo) from over-proliferating.
Tyria jacobaeae is used in conjunction with Longitarsus jacobaeae (the Tansy ragwort flea beetle) for Tansy population control.
Although Tyria jacobaeae will feed on a couple of native plant species, it is my understanding that the frequency of this occuring does not seem to be of concern.
How you want your letter signed:  Bug aficionado

Cinnabar Moth Caterpillar

Dear Bug aficionado,
Thanks for sending us a new image of a Cinnabar Moth Caterpillar and also thanks so much for the informative description.

Letter 3 – Cinnabar Moth Caterpillars

 

what is this caterpillar
Bugman,
Found about 7 of these cuties on a plant out back , in Beaverton ,OR. Looked through the internet with no luck. thought you would be a great place to look. thank you for you attn:
Helen Ferguson

Hi Helen,
Your caterpillars are Cinnabar Moth Caterpillars, Tyria jacobaeae, a species, that according to BugGuide, was “Introduced from Europe as a control for introduced weedy Ragwort, the host plant for its caterpillars, which is toxic to livestock.” The Cinnabar Moth is now well established in Oregon and Washington.

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 – Cinnabar Moth Caterpillar

 

Subject: HELP
Location: Oregon
July 26, 2014 10:48 am
We have a caterpillar that is going to turn into a cinnabar moth, we already know what bug it is but it just went into a cocoon (yay!). How long will it be in a cocoon?
Signature: Seriously bugged

Cinnabar Moth Caterpillar
Cinnabar Moth Caterpillar

Dear Seriously bugged,
According to Bug Life:  “Caterpillars are feeding from July – early September and are initially pale yellow but soon develop bright yellow and black stripes to deter predators. … The caterpillars overwinter as pupa in a cocoon under the ground. The adult moths emerge around mid May and are on the wing up until early August, during which time males and females will mate and eggs are laid.”
  If that is accurate, you will not experience eclosion until next spring.

Letter 2 – Cinnabar Moth Caterpillar

 

Subject:  Tyria jacobaeae moth caterpillar
Geographic location of the bug:  Silverdale, WA
Date: 07/14/2018
Time: 04:22 AM EDT
Your letter to the bugman:  I thought you might like a photo of a Tyria jacobaeae (Cinnabar) moth  caterpillar, a species introduced into North America to help keep it’s host plant, Tanacetum vulgare (Tansy ragwort- flower shown  in photo) from over-proliferating.
Tyria jacobaeae is used in conjunction with Longitarsus jacobaeae (the Tansy ragwort flea beetle) for Tansy population control.
Although Tyria jacobaeae will feed on a couple of native plant species, it is my understanding that the frequency of this occuring does not seem to be of concern.
How you want your letter signed:  Bug aficionado

Cinnabar Moth Caterpillar

Dear Bug aficionado,
Thanks for sending us a new image of a Cinnabar Moth Caterpillar and also thanks so much for the informative description.

Letter 3 – Cinnabar Moth Caterpillars

 

what is this caterpillar
Bugman,
Found about 7 of these cuties on a plant out back , in Beaverton ,OR. Looked through the internet with no luck. thought you would be a great place to look. thank you for you attn:
Helen Ferguson

Hi Helen,
Your caterpillars are Cinnabar Moth Caterpillars, Tyria jacobaeae, a species, that according to BugGuide, was “Introduced from Europe as a control for introduced weedy Ragwort, the host plant for its caterpillars, which is toxic to livestock.” The Cinnabar Moth is now well established in Oregon and Washington.

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.

    View all posts
  • 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.

    View all posts
Tags: Cinnabar Moth

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