Hundreds of millions of years ago, gigantic insects once roamed the planet (including a dragonfly that measured 28 inches). Why have insects since become so small? The most important reason for this is due to the limited size of the insects’ air pipe. When the oxygen content in the air is high, as it was millions of years in the past, the insects can grow to staggering sizes. But if the oxygen in the air is more limited, as it is today, then the bottleneck in the air pipe becomes a restricting factor.
It might be a good thing that insects have evolved to be so small because even the sight of one can send a shiver down people’s spines. But there are still several species around the world that can almost reach the size of insects from the past. Most of them reside in remote rainforests, rarely encountered by people. There are multiple ways to measure size: body and leg length, weight, volume, wingspan, and even horn size. Despite an element of subjectivity to any ranking, this list will take all potential factors into account.
#10 Largest Insects – Hercules Beetle
Named after the famous hero of Greek mythology, this enormous species of rhinoceros beetle hails from the rainforests of Central America, South America, and the Caribbean islands. The most prominent characteristic is the huge horn that extends from the thorax (as well as a second horn that emerges from the head) of the male beetle. The female completely lacks this unique accouterment.
As a result, the male Hercules beetle can measure up to 7 inches long (depending on its nutritional intake and some environmental conditions), but the horn makes up nearly half of the entire body length and so it’s difficult to make direct comparisons to other types of insects. The beetle’s larval stage, which lasts about two years and features three different metamorphosis stages, can grow nearly 5 inches in length as well.
Read more about the gigantic Hercules beetle here.
#9 Largest Insects – Titan Beetle
Measuring up to 6.5 inches long, the titan beetle is endemic to the Amazon rainforests. Although technically smaller than the Hercules beetle, this species actually has a much bigger body, since it completely lacks a horn of any kind. When threatened, the beetle will make a hissing sound and attempt to defend itself. The large mandibles and strong jaw give it a powerful biting force that can pierce human skin and even snap a pencil in half.
The larva of this beetle has never actually been observed by scientists, but it’s been estimated, based on the size of boreholes of trees, that the larvae can grow up to an astonishing foot long. It’s believed that the larva gathers enormous energy so that it will not need to feed as an adult. The Titan is so large that its wings cannot take off from the ground. It must launch from a tree in order to fly.
Read more about beetles, in general, here.
#8 Largest Insects – Stick Insects
The stick insects (also known by many other names, including walking sticks, leaf insects, and ghost insects) are a vast order of insects that consists of than 3,000 species, almost all of them characterized by a spindly, flat, tube-like appearance. They have evolved the ability to hide from predators by blending in with the very branches and leaves they resemble. Some even wield lichen or mossy outgrowth to make the camouflage appear extra convincing.
Most species of stick insects measure at least a foot long. The longest of all stick insects (and insects in general) is a species called Phryganistria chinensis. First discovered in China in 2016, it can reach 25 inches long, or about the size of that ancient dragonfly. The next two largest stick insect species measure about 22 inches. Despite their impressive length, however, the stick insect’s flat, tube-shaped body means that they weigh only a fraction of what you’d expect.
Read more about the spindly stick insects here.
#7 Largest Insects – Goliath Beetles
The goliath beetle is a genus of five currently recognized species that inhabit the tropical rainforests of Africa. The most prominent physical characteristics are the striking and unusual patterns and markings on their back. While these beetles only measure about 3 to 4.5 inches long, they easily make up for it with their impressive bulk. An adult beetle weighs more than 2 ounces, which is quite heavy for an insect. But this actually pales in comparison to the larval stage, which weighs 3.5 ounces and reaches almost 10 inches in length, making it one of the largest insects on the planet by almost any metric. Little information is actually known about the behavior of wild larvae, however.
#6 Largest Insects – Moths
Moths belong on this list on account of their huge wingspan. While there are many impressive species, the atlas moth, which hails from the tropical forests and shrublands of Asia, is probably the largest of its kind. It features a wingspan of up to 11 inches and a wing surface of about 25 square inches. Only the white witch, Attacus Caesar, and Hercules moths come close to eclipsing it, although, given their different wing shapes, it’s difficult to make a direct comparison between them. Curiously, the body of the atlas moth is disproportionately small in comparison to the orange and white wings, which almost look like brilliant, swirling jewels.
Read more about the fascinating world of moths here.
#5 Largest Insects – Giant Weta
The weta, which actually means “god of ugly things” in the indigenous language of Maori, is completely endemic to New Zealand and its surrounding offshore island. These large flightless crickets grow up to 4 inches long and weigh about 2.5 ounces. There are 11 recognized species of giant wetas which live in trees and shrubs but come down to the ground for mating. When they’re threatened, the wetas can defend themselves with their sharp, spiny legs.
Since New Zealand was almost completely free of many mammalian species before the arrival of people, scientists believe that the wetas evolved to occupy a similar niche as rodents; hence, their rodent-like size. But the introduction of actual rodents to the island with each new wave of colonization had a devastating effect on weta numbers. Some populations are now under the protection of the government and have recovered slightly, but they still face many challenges.
#4 Largest Insects – Butterflies
There are many examples of massive butterflies, including the Jamaican swallowtail, Miranada birdwing, and Rippon’s birdwing, but the Queen Alexandra’s birdwing stands above the rest. Named in honor of Queen Alexandra, who was at the time the wife of King Edward VII of Britain.
This inhabitant of New Guinea is the largest species of butterfly in the world. It exhibits a strong degree of sexual dimorphism, meaning that the sexes have radically different appearances. The females are the larger of the two sexes with a body size of up to 3 inches and a wingspan of 11 inches; they also have brown wings with white markings arranged into two rows near the tips. The males have thinner and more angular wings, measuring about 6 to 8 inches from tip to tip, with black central bands and iridescent bluish-green outer areas.
Read more about butterflies here.
#3 Largest Insects – Tropidacris Grasshoppers
Tropidacris is a genus of grasshoppers that contains three different species. This genus doesn’t have a standard name, so instead, it merely goes by the scientific name of Tropidacris. Found scattered across Central and South America, these grasshoppers are among the largest of their kind with a body measuring up to 5 inches.
While the nymphs sometimes exhibit black and yellow warning colorations possibly to dissuade predators, the adults are more green, yellow, and brown to help provide camouflage against the backdrop of the surrounding vegetation. Their brilliant multi-colored wings, which measure about 9 inches from tip to tip, kind of resemble leaves. Otherwise, they look like oversized grasshoppers.
You can read more about grasshoppers here.
#2 Largest Insects – Tarantula Hawks
The tarantula hawk is a group of several spider wasp species. Their names are derived for their tendency to consume tarantulas, which can make for quite a gruesome process. The wasp will immobilize the spider with its sting and then bring back the unfortunate creature to the nest. The newly hatched larva will then consume the tarantula whole. Once it has reached the adult phase, the largest species of tarantula hawks have a length of 2.7 inches and a wingspan of 4.5 inches. For an unfortunate human, an adult wasp can deliver an excruciating sting. But unless it triggers an allergic reaction, the sting shouldn’t require serious medical attention.
Read more about wasps here.
#1 Largest Insects – Mydas Flies
The mydas is a large family of flies that contains nearly 500 separate species. Most of these are endemic to arid or semiarid regions all over the world. As their main means of defense, some species have evolved the ability to mimic the more dangerous stinging wasps and bees. This is intended to trick predators into avoiding them. The largest species of all the mydas, which simply goes by the scientific name of Gauromydas heros, measures up to 2.8 inches long with a wingspan of 3.9 inches, making it the largest fly on the entire planet.
Read more about flies here.
That was our list of the top 10 largest insects! Next: The Top 10 Largest Birds of Prey