Caterpillars are the larval stage of butterflies and moths. They hatch from eggs and spend their time eating and growing until they are ready to form a chrysalis or cocoon and transform into their adult form.
Most caterpillars are quite small, often less than an inch long. However, some species can grow to much larger sizes before they pupate. These giant caterpillars are remarkable to encounter due to their immense size relative to their regular-sized relatives.
So what constitutes a “huge” caterpillar? There are several species around the world that merit that description. Some key examples include:
Atlas Moth Caterpillar
The atlas moth (Attacus atlas) lives in tropical forests across Asia. It has one of the largest wing spans of any moth species, stretching 10-12 inches across in adulthood. To reach this massive size, its caterpillars grow extraordinarily large as well.
Atlas moth caterpillars can reach lengths of 4 inches or more. Their bulky bodies are mottled green with small yellow and red speckles. Small spiny projections cover their body, an effective defense against predators trying to eat them.
Despite their intimidating appearance, atlas moth caterpillars are harmless to humans. They use their strong jaws to voraciously chew through the leaves of fruit, cinnamon, and citrus trees. After several molting cycles, they are ready to spin a silken cocoon and enter the pupal stage.
Hercules Moth Caterpillar
A close relative of the atlas moth is the Hercules moth (Coscinocera hercules), found in rainforests from Australia to New Guinea. It holds the record for the largest wing span of any insect in the world, sometimes exceeding 1 foot across.
As you might guess, the Coscinocera hercules caterpillar grows remarkably large as well. It can reach lengths over 6 inches, making it longer than some people’s hands! Its fat green body is dotted with yellow knobs and spines for protection.
Despite their scary appearance, Hercules moth caterpillars are solitary creatures that pose no threat to human health. They chew through the leaves oftrees and shrubs at a voracious pace. Within a few weeks they are ready to pupate on the forest floor. Their huge size makes them vulnerable to predation at this stage, so most do not make it to adulthood. Those that do emerge as the world’s largest moth species.
Luna Moth Caterpillar
With its pale green wings decorated with sweeping tails, the luna moth (Actias luna) has an ethereal beauty. This species is found across North America in wooded regions.
Luna moth caterpillars grow up to 4 inches long, with vivid lime green bodies. Unlike some other giant caterpillars, they lack major spikes or projections for defense. Instead, they have subtle yellow and blue dots along their backs, which serve to camouflage them against leafy backgrounds.
These caterpillars feed on walnut, hickory, birch and other deciduous tree leaves. They spin thin but tough silk cocoons when they are ready to pupate, often in leaf litter on the ground. Their major predators include rodents, parasitic insects, and birds.
Regal Moth Caterpillar
With its large size and eye-like spots, the regal moth (Citheronia regalis) caterpillar earns a spot on this list. It can grow to 4 inches long, with a fat green body dotted with orange, yellow, black, and white markings.
This species is native to North America, ranging from Mexico up into Canada. As larvae, regal moth caterpillars rely on oaks, pecans, walnuts, and other trees as food sources. They have small spines across their bodies that serve to protect them from predators.
While they may look exotic, regal moth caterpillars are harmless to humans. The greatest threat they face are parasitic wasps, flies, and other insects that lay eggs on or inside them. Those that survive eventually spin silk cocoons and transform into large, beautiful regal moths as adults.
Polyphemus Moth Caterpillar
The polyphemus moth (Antheraea polyphemus) is another giant silk moth species of North America. Its green caterpillars grow up to 4 inches in length, fattening up on oak, willow, birch, and maple leaves until they are ready to pupate.
Polyphemus moth caterpillars have yellow or white stripes along their bodies for camouflage. Prominent red or orange tubercles also help break up their outline, acting as a defense against predators like birds, rodents, and parasitoid wasps. These spiny protrusions are harmless to humans if handled carefully.
Once fully grown, the caterpillar finds a protected spot and spins a silken cocoon to pupate in. About 1-2 weeks later, the adult moth will emerge ready to start the breeding cycle again. The total lifespan of a polyphemus moth is only about 1 week, so they have limited time to find mates and reproduce.
Spicebush Swallowtail Caterpillar
One of the most striking caterpillars from North America is that of the spicebush swallowtail butterfly (Pterourus troilus). Growing to lengths of 2-3 inches, it is much smaller than the giant silk moth caterpillars mentioned earlier but still substantial in size compared to many other species.
These caterpillars have plump green bodies with large yellow and black “eye spot” markings along their backs. Their appearance mimics small snakes, helping to deter predators. If threatened, they can also extend two orange osmeteria just behind their heads that release a foul smell and taste to repel attackers.
Spicebush swallowtail larvae feed on sassafras, prickly ash, and namesake spicebush plants. They can strip these host plants of leaves very quickly while they grow. Within a couple weeks they are ready to form a chrysalis and complete their metamorphosis into a beautiful swallowtail butterfly.
Io Moth Caterpillar
The peculiar caterpillar of the io moth (Automeris io) deserves honorable mention here. Native to North America, io moth larvae reach 2-3 inches in length when fully grown. Their bodies are adorned with arrays of branched spines in black, yellow, and red.
This colorful and complex pattern helps the caterpillars blend into the leaves and twigs of their host plants, which include birch, willow, and tougher trees like oak, hickory, and hornbeam. The spines are stinging and contain toxins that serve to protect the caterpillar from predators.
When perturbed, io moth caterpillars will raise their heads and flail around, displaying the intimidating appearance of their spines and colors. Luckily for us, contact with humans only results in a minor stinging irritation and is not dangerous. After a few weeks of voracious feeding, the caterpillars spin cocoons and transform into pale green io moths.
Slug Moth Caterpillar
Most giant caterpillars have some sort of protective spines, toxic hairs, or warning coloration to deter predators. But the slug moth caterpillar takes things in the opposite direction. Growing up to 4 inches long, its body is short, fat and rounded with no major projections.
This gives slug moth caterpillars a peculiar slug-like profile in addition to their slow, gliding movements along branches. The lack of spines does make them more vulnerable to predators and parasitoids, however. Some species have adapted by feeding only on toxic plants, accumulating the toxins from the leaves they eat.
These odd caterpillars can be found across North America feeding on cherry, oak, elm and other trees. They get their name from the adult moths they eventually transform into, which have relatively stout, shortened bodies compared to other moth species.
Cecropia Moth Caterpillar
One of the largest and most striking caterpillars from eastern North America is that of the cecropia moth (Hyalophora cecropia). These chunky larvae grow up to 5 inches long, with numerous small bumps and projections scattered across their bodies.
Cecropia caterpillars come in a range of colors and patterns to help camouflage them against tree bark and leaf litter. Some are apple green with black and yellow dots, while others have blue, orange, or red coloration. Regardless of the pattern, they certainly stand out due to their large size.
These moth larvae rely on deciduous trees and shrubs like maple, birch, cherry, willow, and apple as their primary food sources. They are voracious eaters, capable of stripping leaves from branches at an impressive pace. Despite their scary appearance, cecropia caterpillars do not sting or pose any danger to humans.
Largest Caterpillars in the World
The largest caterpillar species in the world is arguably the larva of the giant sphinx moth (Pseudosphinx tetrio). These chunky caterpillars can reach lengths over 6 inches, growing fatter than a human thumb. They feed on a small number tropical trees and are found across parts of Central and South America.
Other contenders for largest caterpillar include the larvae of the Atlas beetle and Hercules beetle. Both grow to around 5 inches long. Found in the jungles of Southeast Asia, these caterpillars rely on decaying wood from dead trees for food and nutrients.
While not a true caterpillar, the witchetty grub from Australia also deserves mention for its extreme size. These are the larvae of giant wood moths and grow up to 6 inches long while feeding on the roots of trees and shrubs before pupating underground.
Key Facts and Summary
Here are some key facts about huge caterpillars:
| Species | Length | Location | Food Sources |
| Atlas moth | 4+ inches | Asia | Fruit, cinnamon, citrus trees |
| Hercules moth | 6+ inches | Australia, New Guinea | Trees and shrubs |
| Luna moth | 4 inches | North America | Walnut, hickory, birch, etc. |
| Regal moth | 4 inches | North America | Oak, pecan, walnut, etc. |
| Polyphemus moth | 4 inches | North America | Oak, willow, birch, maple |
– Most giant caterpillars reach lengths between 4-6 inches when fully grown. The largest ever recorded was the larvae of the giant sphinx moth at over 6 inches long.
– They are found on every continent except Antarctica, but are most diverse in tropical regions like South America, Africa, and Southeast Asia.
– Many large caterpillars have defensive spines, hairs, or coloring to deter predators. Some species take the opposite approach and lack these defenses, relying on camouflage or toxicity instead.
– All giant caterpillars feed on leaves, especially from trees and shrubs. Some rely on a single plant species as a host while others can consume a wide variety.
– Despite their often frightening appearances, big caterpillars do not sting or present any real danger to humans. At most you may get minor irritation from contact with protective spines or hairs.
– After several weeks or months of voracious feeding, giant caterpillars find sheltered spots to pupate, emerging as adult butterflies or moths once metamorphosis is complete.
So in summary, “huge” caterpillars are the larvae of some of the world’s largest moth and butterfly species. They come in a variety of colors and forms to camouflage and defend themselves. Though they may look exotic or even alarming, giant caterpillars are harmless herbivores just focused on eating and growing in their youth before transitioning to the final winged stage of their complex life cycles.
