The Largest Insect Ever Existed Was a Giant 'Dragonfly'

The largest known insect that ever existed was a giant 'dragonfly' species known as Meganeuropsis. It had a wingspan of up to 75 cm (2.5 feet) and a body length of up to 47 cm (18.5 inches), with an estimated weight of over 1 pound (450 g), making it similar in size and weight to a crow. This made Meganeuropsis significantly larger than any modern dragonfly. It was a formidable predator.

Meganeuropsis Permiana The Giant Dragonfly

Meganeuropsis permiana was a predator and its large size allowed it to prey on small vertebrates, such as amphibians and small mammals. It is thought that the large size of Meganeuropsis permiana was possible due to the high oxygen levels in the atmosphere at the time.

Meganeuropsis permiana was first discovered in the Wellington Formation of Kansas, United States. The Wellington Formation is a sedimentary rock formation that dates back to the Early Permian period, about 290 million years ago. The formation is known for its fossils of insects, fish, and amphibians.  Meganeuropsis permiana has also been found in other parts of the world, including France, Russia, and China.

The Largest Insect Ever Giant "Dragonfly"
Fossil of a Meganeuridae The largest insect that ever existed was a dragonfly.

Meganeuropsis permiana Detailed Description

Meganeuropsis permiana is an extinct genus of griffinfly, order Meganisoptera, known from the Early Permian Wellington Formation of North America, and represents the largest known insect of all time. Meganeuropsis existed during the Artinskian age of the Permian period, 290.1–283.5 mya.


The wingspan of Meganeuropsis permiana is estimated to have been between 28 and 75 centimeters (11 and 30 inches). This makes it the largest known insect that has ever lived.

Body size

The body size of Meganeuropsis permiana is estimated to have been between 17 and 43 centimeters (7 and 17 inches). This makes it larger than a crow.


Meganeuropsis permiana was a predator and its large size allowed it to prey on small vertebrates, such as amphibians and small mammals. It is thought that it may have also eaten insects.


Meganeuropsis permiana became extinct at the end of the Permian period, about 252 million years ago. The extinction of Meganeuropsis permiana and other large insects is thought to have been caused by a combination of factors, including a decline in oxygen levels, climate change, and the arrival of the first birds.

How did Meganeuropsis permiana get very big?

Here are some of the theories about how insects of the Carboniferous period were able to grow so large:

Oxygen levels and atmospheric density.

The way oxygen is diffused through the insect's body via its tracheal breathing system puts an upper limit on body size, which prehistoric insects seem to have well exceeded. It was originally proposed hat Meganeura was able to fly only because the atmosphere at that time contained more oxygen than the present 20%.

Lack of predators.

Other explanations for the large size of meganeurids compared to living relatives are warranted. Bechly suggested that the lack of aerial vertebrate predators allowed pterygote insects to evolve to maximum sizes during the Carboniferous and Permian periods, perhaps accelerated by an evolutionary "arms race" for increase in body size between plant-feeding Palaeodictyoptera and Meganisoptera as their predators.

Aquatic larvae stadium.

Another theory suggests that insects that developed in water before becoming terrestrial as adults grew bigger as a way to protect themselves against the high levels of oxygen.

Facts about The Largest Dragonfly Ever Existed

Though always associated with the modern-day dragonflies due to their appearance, considering the various structural and other characteristic differences between them, these insects were often classified as griffinflies. 

The term 'Meganeura' means large-veined, and these insects had similar vein patterns in their wings. However, the vein patterns found in the wings of dragonflies usually vary.

It is believed that their hunting and preying methods were quite similar to those of modern-day dragonflies. However, it may have attacked many more organisms owing to its larger size.
Their large eyes made it possible for them to watch out for prey while the spine on their legs enabled them to get hold of it.

Their wings had a network of veins. Moreover, they were heavily veined and had cross braces for strength unlike those of the present-day dragonflies that have delicate wings.

The male insects would mate by taking hold of the female with the help of appendages in the front.

They believe that it was impossible for the massive bodies of these insects to survive in the present-day atmospheric conditions and that this may have led to their extinction. (The oxygen content in today's atmosphere is up to 21% and back in the Carboniferous period, it was up to 35%.)

The breathing mechanism of these insects allowed the passage of air through a system of tracheal tubes, transporting the oxygen directly to the internal tissues.

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