Blue caterpillars stand out with their unusual coloring. Ranging from light blue to rich indigo tones these little creatures captivate with their vibrant hues. But what exactly are blue caterpillars and what makes them develop this distinctive coloration? Let’s take a closer look at these fascinating insects.
What Are Blue Caterpillars?
Caterpillars are the larval stage of butterflies and moths During this phase, they voraciously consume plant matter to fuel their growth and development.
While most caterpillars have a green coloration, some develop blue or blue-green tones as they mature. This unusual shade likely serves as a defense mechanism, making them appear unappetizing or even poisonous to potential predators.
Blue caterpillars are not inherently toxic, But their vivid coloring advertises the message “I don’t taste good!” This allows them to avoid becoming someone else’s meal,
When Do They Turn Blue?
The timing of a caterpillar’s color change varies by species. Some, like the white-dotted prominent, are born blue-green and turn solid green as they age.
Others, such as the Columbia silk moth and regal moth caterpillars, are brightly colored in their youth but take on blue-green hues nearing pupation.
And a few, including the Cecropia moth, flash brilliant blue tubercles during their final instar stage.
Whenever it occurs, this dramatic color shift signals the caterpillar’s transition toward adulthood.
What Do Blue Caterpillars Eat?
Like all caterpillars, blue varieties are voracious eating machines. Their preferred diets depend on the species but often include:
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Tree leaves – Oak, hickory, ash, alder, and beech are common hosts.
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Ornamental plants – Lilacs, roses, and hemp.
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Fruiting plants – Grapevines are a favorite of Abbott’s sphinx moth caterpillars.
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Agricultural crops – A few become pests of walnut, hazelnut, and apple orchards.
While they may defoliate their host plants, most blue caterpillars do minimal ecological damage. Outbreaks are naturally controlled by predators like wasps, reducing their pest potential.
Where Do Blue Caterpillars Live?
Blue caterpillars inhabit a variety of ecosystems across North America. Some of their typical habitats include:
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Deciduous forests – Rich communities of oak, hickory, ash, and maple trees.
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Orchards and plantations – Hazelnut, walnut, and apple groves.
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Urban parks and gardens – Anywhere their host trees or flowers grow.
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Arid scrublands – In the Southwest, species like the Calleta silkmoth caterpillar thrive.
The caterpillar’s range depends on its host plants and climate adaptability. But blue varieties exist coast-to-coast, from Canada to Mexico.
Are Blue Caterpillars Poisonous?
Luckily, most blue caterpillars are not dangerous to humans. Their coloring is simply a warning display, not an indicator of toxicity. However, a few exceptions exist:
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Some species have poison glands that can cause skin irritation, like the spun glass slug caterpillar. Handle these with care.
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Large, spiny varieties may look intimidating but their bristles rarely pierce skin.
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Outbreaks of agricultural pest species, while not toxic, can damage crops. Control may be warranted.
While not poisonous, blue caterpillars don’t make ideal pets. Their voracious appetites and short adult lifespans make rearing them challenging for beginners. But they are fascinating to observe in the wild!
Notable Blue Caterpillar Species
Let’s take a closer look at some of the most striking blue caterpillar varieties:
Regal Moth Caterpillar
One of the world’s largest caterpillars, these blue-green beasts can reach nearly 5 inches long! They feast on hickory, walnut, and hazelnut leaves before spinning enormous cocoons to transform within.
Cecropia Moth Caterpillar
Clad in brilliant blue and orange tubercles, the Cecropia caterpillar enchants onlookers as it consumes a wide variety of trees and ornamental plants. One of North America’s giant silk moths, its cocoon produces luxurious satin thread.
Spiny Oak Slug Moth Caterpillar
This aptly named species wears a spiky crown of color. Its green body is adorned with yellow spines tipped in blue as it matures. Oaks are their foodplant of choice across the Eastern and Central states.
Columbia Silkmoth Caterpillar
Beginning life as a bright green caterpillar, the Columbia silk moth transforms to a subtle blue-green hue before spinning its cocoon. Its gray adult form camouflages this moth well as it flies through Eastern larch and alder forests.
Forest Tent Caterpillar
Perhaps the most recognizable blue caterpillar, the forest tent sports vibrant blue stripes contrasted with white and black. These social creatures build large silken nests in trees, which they share with their siblings.
The Life Cycle of Blue Beauties
Like all butterflies and moths, blue caterpillars go through a complete metamorphosis as they develop. Their life cycle contains four stages:
Egg – After mating, the adult female lays eggs on the caterpillar’s host plant. These tiny ovals contain the next generation.
Larva – The egg hatches and the caterpillar, or larva, emerges. It immediately starts consuming plant material, growing and shedding its exoskeleton several times.
Pupa – Once fully grown, the caterpillar forms a protective chrysalis or cocoon around itself. Inside, its tissues transform into the wings, legs, and organs of the adult form.
Adult – After undergoing this astounding metamorphosis, the adult butterfly or moth emerges from the pupa. It lives just long enough to reproduce and start the cycle anew.
For a brief time, we get to enjoy these creatures in their larval form, flashing their brilliant blues as a reminder of nature’s capacity for wonder. Appreciating blue caterpillars gives us an opportunity to observe an often overlooked stage of insect life unfolding right in our own backyards!
How to identify caterpillars
A caterpillar is the larval stage of a moth or butterfly. It is the second part of their four-stage life cycle: egg, larva, pupa and adult. Many caterpillars look very different as they grow, so weve described the larger stages of the caterpillars growth when theyre often more obvious. Some are easily spotted on their favourite food plants. Here are some of the species youre likely to see!
When & where: August-June. A variety of habitats including gardens, but especially damp grassland, marshes and boggy areas.
Description: Up to 7 cm long. Dark and covered with brown hairs and golden speckles. A row of white hairs runs down each side of the body.
Drinker moth caterpillar ©Chris Lawrence
Drinker moth caterpillar ©Tom Marshall
Drinker caterpillar © Guy Edwardes/2020VISION
Young drinker caterpillar © Vaughn Matthews
When & where: June-April, most obvious in spring. Often heathland and coastal grassland.
Description: Up to 7 cm long. Hairy, with long dark hairs on the sides of the body and shorter orange hairs on top. Young caterpillars are dark with orange bands.
Fox moth caterpillar ©David Longshaw
Fox moth caterpillar by Tom Hibbert
Fox moth caterpillar by David Longshaw
Early instar fox moth caterpillar © Frank Porch
When & where: August-June. A variety of habitats including grassland, heathland, fens, and hedgerows. Often found crawling across paths in spring.
Description: Young caterpillars in late summer and autumn are small and bluish with orange diamond patterns. More obvious in spring, when caterpillars are large and extremely furry, with long, orange-brown hairs. There are black bands between each body segment, and white dashes on each side.
Oak eggar caterpillar © Tom Hibbert
Oak eggar caterpillar © Frank Porch
Oak eggar caterpillar © Vaughn Matthews
Early instar oak eggar caterpillar © Frank Porch
Early instar oak eggar caterpillar © Frank Porch
When & where: August-June. A wide range of habitats including gardens.
Description: Up to 6 cm long. An extremely hairy caterpillar, known as the “woolly bear”. Mostly black and ginger, with longer white hairs.
Garden tiger caterpillar © Frank Porch
Garden tiger caterpillar ©Amy Lewis
Garden tiger caterpillar © Faye Davies
Garden tiger caterpillar © Brian Eversham
When & where: July-September. Found on ragwort in most grassy habitats.
Description: The caterpillars of this moth are distinctive, with black and yellow stripes – warning predators that they taste terrible. Theyre easily spotted feeding on ragwort.
Cinnabar moth caterpillar ©Andrew Hankinson
Cinnabar caterpillars © Jon Hawkins – Surrey Hills Photography
Cinnabar caterpillar © Niall Benvie/2020VISION
When & where: June-September. A variety of habitats, including gardens. Often where rosebay willowherb is found.
Description: Up to 8.5 cm long. A chunky green or brown caterpillar, with several eyespots at the front end and a spiky tail at the rear.
Elephant hawk-moth caterpillar ©Dawn Monrose
Elephant hawk-moth caterpillar © Tom Hibbert
Elephant hawk-moth caterpillar © Vaughn Matthews
Elephant hawk-moth caterpillar © Tom Hibbert
When & where: July to September. Widespread in southern England and Wales. Found in a variety of habitats, including gardens.
Description: Up to 8.5cm long. Green and chunky, with purple and white stripes on the body and a black and yellow horn on the rear.
Privet hawk-moth caterpillar ©Roy Bedborough
When & where: June to September. Widespread in a variety of habitats, including parks, gardens and wetlands. They feed on poplars and willows.
Description: Recently hatched caterpillars are tiny and black, with two long, whip-like tails. Older caterpillars are plump and green, with a dark, white-edged saddle. The head is surrounded by a pink patch, with false eyes making it look like a giant face. They still have two thin tails. When theyre fully fed and ready to pupate, they turn a purplish colour.
Puss moth caterpillar ©Vaughn Matthews
Puss moth caterpillar © Vaughn Matthews
Puss moth caterpillar © Tom Hibbert
Newly hatched puss moth caterpillars © Frank Porch
When & where: April-July. A range of open habitats, including gardens. Feeds on mulleins and buddleia.
Description: Distinctive whitish caterpillars, with yellow splodges across the body and large black spots.
Mullein caterpillar © Frank Porch
Mullein moth caterpillar ©Chris Lawrence
Mullein caterpillar © Frank Porch
Mullein caterpillar © Frank Porch
When & where: August-June. Scrubby habitats including hedgerows, woodland and gardens.
Description: Black with long, greyish-white hairs. On top it has a pair of red lines, with a row of white blotches either side of them. A red line runs along each side. The hairs can be an irritant.
Yellow-tail moth caterpillar ©Chris Lawrence
Yellow-tail caterpillar © Tom Hibbert
Yellow-tail caterpillar © Tom Hibbert
When & where: August-May. Scrubby habitats, including coastal scrub.
Description: Black with long brown hairs, two red spots on top and a line of white marks along each side. Found in conspicuous communal webs on food plants. The hairs cause skin irritation.
Brown-tail moth caterpillar © Tom Hibbert
Young brown-tail caterpillar © Chris Lawrence
Brown-tail caterpillar © Frank Porch
When & where: June-October. Grasslands, wetlands, heathlands, open woodlands, and coastal habitats.
Description: Black with brown hairs. Row of alternating red spots and lines on top, with a line of white dashes either side. Row of spots and dashes on each side. Rests with slight hunch in the back.
Knot grass caterpillar © Vaughn Matthews
Knot grass caterpillar © Frank Porch
Knot grass caterpillar © Frank Porch
When & where: May-July. Common in a range of habitats where common nettle is present.
Description: Up to 4.5 cm. Black with black spines and small white dots. Found in communal webs on common nettles.
Peacock caterpillar © Margaret Holland
Peacock caterpillars ©Vaughn Matthews
Peacock caterpillars © Jon Hawkins – Surrey Hills Photography
When & where: May-September. Commonly found in a variety of habitats including woodland, parks and gardens.
Description: A funky-looking grey and black caterpillar, with large tufts of hair, including a mohawk of yellow tufts on the back. Large caterpillars can often be spotted in late summer on a range of shrubs and trees.
Vapourer caterpillar © Pete Richman
Vapourer caterpillar © Les Binns
Vapourer moth caterpillar ©Tom Hibbert
When & where: June-October. Found on a wide variety of deciduous trees and other plants, including bramble.
Description: A striking bright green caterpillar, with black bands between its body segments, yellow/whitish hairs, a row of yellow tufts on top and a red tuft at the rear.
Pale tussock caterpillar ©Lizzie Wilberforce
Pale tussock caterpillar © Frank Porch
Pale tussock caterpillar © Frank Porch
Sawflies are a group of flies, whose larvae look very similar to moth and butterfly caterpillars. The larvae are usually 1-4 cm long, but come in an impressive variety of colours. One way to spot a sawfly larva is to count the legs – they also have six true legs, but usually have six or more pairs of the stumpy prologs, whereas caterpillars have five or fewer.
Rose sawfly larvae ©Les Binns
Iris sawfly © Tom Hibbert
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Carnivorous UNDERCOVER caterpillar | Wild Isles – BBC
FAQ
What do blue caterpillars turn into?
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These caterpillars, after the larval stage, form a chrysalis and undergo a transformation to become the iconic blue butterfly with its bright blue wings.
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These are other species of blue butterflies that also undergo a similar life cycle, with caterpillars transforming into their respective butterfly forms through the pupa stage.
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This butterfly’s lifecycle is unique, with the caterpillar mimicking ant grubs to gain protection and food in ant nests before pupating and emerging as a butterfly.
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This endangered butterfly also undergoes a complete metamorphosis, with caterpillars feeding on specific plants before pupating and transforming into adult butterflies.
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This butterfly’s caterpillars sometimes produce a sweet liquid to attract ants for protection, and the adult butterfly has “tails” on its hind wings that it can quiver to distract predators.
What is the name of the blue caterpillar?
| Caterpillar | |
|---|---|
| Created by | Lewis Carroll |
| In-universe information | |
| Alias | Hookah-Smoking Caterpillar, Absolem |
| Nickname | The Blue Caterpillar |
What are the blue caterpillars to feed lizards?
- Low in chitin, making them easier for reptiles to digest compared to other feeder insects.
- Their vibrant blue-green color can entice picky eaters and stimulate appetite.
- Suitable for a variety of pets, including lizards, amphibians, tarantulas, and birds.
What does a blue horn caterpillar turn into?
Both caterpillars turn into large moths with four- to six-inch wingspans in colors ranging from brown and gold to pink and grey. They often are mistaken for small hummingbirds when they fly during the day and hover helicopter style to nectar on flowers, which is why they are also called Hummingbird or Hawk Moths.
What are the most common blue caterpillars?
Blue caterpillars come in many different species, but some of the most common blue caterpillars include: The Eastern Tailed Blue (Cupido comyntas) is one of the most common blue caterpillars. These caterpillars are mostly blue in color with some black spots and reach around 1 inch in length.
What colors do caterpillars come in?
Most caterpillars are green with blue undertones, appearing later as they mature. Blue is similar to red in making a species look unappealing or even poisonous. Caterpillars sometimes take darker green nuances, closer to blue, when they need to stand out less in front of predators such as tachinid flies or predatory wasps.
What is a bluebottle caterpillar?
Bluebottle caterpillars are any of several swallowtail species that have blue, green, or turquoise larvae with striking eye-spots. Some common species are the Eastern Black Swallowtail, Spicebush Swallowtail, and Zebra Swallowtail. The Marine Blue (Leptotes marina) has a greenish-blue caterpillar with white and orange bands and black tufts.
What does a blue metalmark caterpillar look like?
These caterpillars are mostly blue in color with some black spots and reach around 1 inch in length. They feed on plants in the pea family before forming a chrysalis and emerging as butterflies in the summer. The Blue Metalmark (Calephelis borealis) caterpillar has a vibrant blue color with orange spots.
Are blue caterpillars harmful to plants?
Blue caterpillars are more detrimental to host plants than to humans. Some species dig tunnels under tree bark, essentially hurting the health of the host. Most types of blue caterpillars have no major impact on the host species, creating limited damages to hosts.
What do blue caterpillars do to their host plants?
Blue caterpillars are more detrimental to host plants than to humans. Some species dig tunnels under tree bark, essentially hurting the health of the host. Most types of blue caterpillars have no major impact on the host species either. They create limited damages to hosts.