Although the species of meganulon, the origin of Megaguirus, were first depicted in the 1956 movie Rodan, the monster itself did not appear until its debut in 2000. Megaguirus was first mentioned in the movie Godzilla vs. Megaguirus after a swarm of meganulon absorbed energy from Godzilla and quickly fled to a flooded section of Tokyo. After diving into the flood waters, the entire swarm latched on to an enormous, mutated version of meganulon. This mutated creature, regarded as the queen, begins to molt once enough energy had been obtained. After leaving behind its exoskeleton, Megaguirus rose above the water's surface and entered the skies of Tokyo.
Immediately after getting above water, Megaguirus began its rampage of Tokyo, destroying numerous buildings by creating super sonic shock waves with its wings. The Japanese military, already deployed to the city to assist in evacuating residents caught in the flood, was helpless to stop Megaguirus. In addition to being practically immune to bullets, its wings emitted a piercing buzz which forced people to stop what they were doing and cover their ears in pain. Before leaving the city, the creature leveled a skyscraper and caused a chain reaction of explosions in several other buildings near where it was born. Several days later, Megaguirus returned to Tokyo in pursuit of Godzilla.
After having its stinger pulled out of Godzilla, Megaguirus uses the newly obtained energy to pick Godzilla up and throw him into a building. Once Godzilla recovered, Megaguirus again stabs him with her stinger, but this time, Godzilla grabs Megaguirus's tail and slams it into the ground and follows through by tackling her. Shortly thereafter, Megaguirus uses the absorbed energy to launch an "atomic blast" which caused Godzilla to collapse. Seemingly having defeated Godzilla, Megaguirus goes in for the kill, but just as she makes her move, Godzilla quickly gets up and bites off Megaguirus's stinger. Stunned, Megaguirus floats backwards from Godzilla, only to be set aflame by his atomic breath. To ensure his victory, Godzilla hits Megaguirus again, causing her to explode into a ball of fire before the burning remains fell to the ground and exploded for a final time.
Similar to nearly every monster in the Godzilla series, Megaguirus was at one point exposed to radioactive materials, resulting in a substantial increase in strength, speed and size. After obtaining energy from the minor meganulon, Megaguirus is able to fly at incredibly fast speeds, up to mach 4. It is able to flap its dragonfly-like wings at super-sonic speeds, creating shock waves that can destroy buildings. Its enlarged tail works similar to the stinger of a scorpion, it jabs its foe and latches on to it. Once the stinger is in Megaguirus's opponent, it can either absorb energy for itself or release a blast of energy composed of its opponents beam weapon. Additionally, while flying, its wings cause electronic disturbances.
Megaguirus has appeared in three video games produced by Atari since Godzilla vs. Megaguirus came out in 2000. Of these, the creature is a playable character in two and an AI-controlled boss or enemy in one.
Godzilla: Save the Earth (2004): One of 18 playable characters in this melee game. Megaguirus is regarded as the fastest creature in the game and retains one of its signature features as an attack, stealing energy through its tail. The game was designed for the Xbox and PlayStation 2 platforms.
Godzilla: Unleashed (2007): One of 26 playable characters in this 3D fighting game. Megaguirus is part of the "Mutant" faction of monsters and remains the fastest character. This game was designed for the Wii and PlayStation 2 platforms.
Godzilla Unleashed: Double Smash (2007): A shorter, less encompassing version of Godzilla: Unleashed designed for the Nintendo DS. However, unlike the console version, in Double Smash, Megaguirus is not a playable character and has a minimal part in the game.
Skeetera from Godzilla: the Series has similar powers as Megaguirus.
This is the first prehistoric insect to fight Godzilla.
There is a useful glitch in Godzilla: Unleashed, where Megaguirus is able to use a beam indefinitely (forever), taking the weapon after stealing the opponents energy first.
The Meganulon are based off of an actual prehistoric species of dragonfly, called Meganeura. These dragonflies lived before the dinosaurs, in the Carboniferous era, and were as large as seagulls. Many giant insects evolved during the carboniferous because of the high amount of oxygen in the air.
In the movie, it is unclear as to whether Megaguirus is prehistoric or extradimensional, because her egg was brought to Earth (or possibly mutated, it never says) by a man-made black hole called the Dimension Tide.
The Meganulon's first appearance was actually in the movie Rodan.