The Giant Insect Longer Than a Hot Dog Crawling Around America

Northern Walkingstick Insect (Diapheromera fermorata)
Melinda Fawver/Shutterstock.com

Written by Kellianne Matthews

Published: July 24, 2024

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Insects all over the Earth come in all shapes and sizes, from pesky mosquitoes to beautiful butterflies. The teeny tiny fairyfly, for example, grows less than 0.25 inches long, while the stick insect Phryganistria chinensis can reach lengths of up to 25 inches long! Many of the biggest insects often live in tropical and temperate regions, but the United States also has some surprisingly large ones. Let’s look at the five largest insects found in the U.S.!  

5. Eastern Dobsonfly (Corydalinae cornutus) – 5.5 Inches

The eastern dobsonfly

Male dobsonflies have long pincer-like mandibles.

Male dobsonflies are pretty intimidating with long, pincer-like mandibles, but they are actually quite harmless. Female dobsonflies, on the other hand — those are the ones you need to watch out for! While females have much shorter mandibles, they are more powerful and capable of leaving a pretty nasty bite. 

Eastern dobsonflies are one of the largest insects in the U.S. Their bodies grow around 5.5 inches long, with a wingspan of up to 5 inches. Primarily near streams throughout the eastern half of the U.S., these large insects spend most of their lives in the water as larvae, using their formidable pincers to snag swimming prey. As adults, eastern dobsonflies only live for a few days. 

4. Polyphemus Moth (Antheraea polyphemus) – 6 Inches

The Polyphemus moth, one of the giant silk moths of North American, shows the bright eyespots on its hindwings which is used to deter predators.

Polyphemus moths are fond of fruit trees, willows, birch trees, maples, and many other plant varieties.

The giant silk Polyphemus moth gets its name from the distinct “eyespot” patterns on its wings. They look like giant eyes, reminiscent of the famous cyclops of Greek Mythology, Polyphemus.

These colossal moths have an average wingspan of around 6 inches, and caterpillars are 3 to 4 inches long. Polyphemus moths live in southern Canada, Mexico, and everywhere in the U.S. except Hawaii, Alaska, Arizona, and Nevada. Despite their large size and abundance, however, they are hard to find due to their excellent camouflage.

3. Luna Moth (Actias luna) – 4 to 7 Inches

Macro of a luna moth against black background. The moth is bright green with golden yellow false eyes visible on its hindwing. Its top wings are edged in russet along the top. The moth is perched on a wing.

Luna moths may have blueish or yellowish tints to their green wings.

The luna moth is an elegant and iconic insect that is easily recognized thanks to its stunning green coloring and elongated wings. These gorgeous wings are typically 4 to 5 inches across, but some have been known to reach lengths of up to 7 inches! Luna moths prefer spending their time in forested areas in the eastern part of the U.S. Their extra-long tails serve as a defense against predators like bats, disrupting their use of echolocation.

Like their adult counterparts, luna moth caterpillars are also bright green. Caterpillars eat a variety of plants, depending on where they live, including persimmon, sumac, hickory, white birch, walnut, and persimmon leaves. Luna moths need to get plenty to eat during their caterpillar stage of life because as adults, they don’t eat at all! They only live around one to two weeks, and they spend that time looking for a mate and laying eggs.

2. Cecropia Moth (Hyalophora cecropia) – 5 to 7 Inches

A cecropia moth is sitting on a huge maple leaf. The Cecropia moth is the largest and heaviest moth in North America.

The cecropia moth is the largest native moth species in North America.

With an impressive wingspan of 5 to 7 inches, cecropia moths are some of the largest insects in the U.S. They have striking colors, with deep red bodies and black, white, and red wings. However, their beauty is short-lived: adult moths only live for about two weeks. In fact, they don’t really have a digestive system or a fully developed mouth! This is because their main objective is to find a mate and produce the next generation. 

Cecropia moth caterpillars can also get pretty big, measuring 4 to 4.5 inches long. Although they are black when they first hatch, caterpillars transition to green with blue, yellow, and orange projections covered in tiny black spikes. 

1. Giant Walking Stick (Megaphasma denticrus) – 7 Inches

Megaphasma denticrus, green giant walkingstick on leaves, Ketapang, December 3, 2022

Giant walking sticks can be tan, brown, rusty brown, and some even have a greenish hue. 

The giant walking stick is the largest insect in the U.S. This incredible creature can grow up to 7 inches long! Like their name, they have long, thin bodies that look just like natural sticks. This provides excellent camouflage from predators and dangers.

Despite their enormous size, giant walking sticks eat leaves and are harmless to humans. One of the coolest things about them though, is that they don’t just look like sticks — they also act like sticks! For example, when it’s windy, giant walking sticks will sway to look like a real stick blowing in the breeze. 

Bonus: White Witch Moth (Thysania agrippina) – 10 Inches

The White Witch Thysania agrippina butterfly. Moth oft he erebidae family with the greatest wing span in world. Here with a wingspan of 28 cm.

The white witch moth is also called the great owlet moth and ghost moth.

Although not native to the U.S., the white witch moth has been spotted on rare occasions in Texas. Native to South America, the largest white witch moth on record had a wingspan as long as a ruler — an astounding 12 inches across! White witch moths have a unique zig-zag pattern on their wings, with brown, cream, and black colors. This provides excellent camouflage in their native rainforest habitats. 


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About the Author

Kellianne Matthews

Kellianne Matthews is a writer at A-Z Animals where her primary focus is on anthrozoology, conservation, human-animal relationships, and animal behavior. Kellianne has been writing and researching animals for over ten years and has decades of hands-on experience working with a variety of different animals. She holds a Master’s Degree from Brigham Young University, which she earned in 2017. A resident of Utah, Kellianne enjoys creating, analyzing movies, and hanging out with her dog and cats.

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