The God Bug, is the ultimate caste member of the Arachnids species and primary ante-penultimate antagonist.
This massive creature is deeply rooted into the planet it is deployed upon and possesses numerous appendages beneath the planet's surface which it uses to capture and kill prey. The fissures it creates are capable of engulfing beings anywhere on the planet, and the bug attacks prey unfortunate enough to fall into them. Behemecoatyl is capable of speaking through other organisms, using their corpses as gruesome puppets.
The God Bug is capable of extending its head from the ground, and appears to share many qualities with the Brain Bug. Its large mouth contains numerous tentacles which allows it to absorb the memories of other organisms - namely humans. It's not known whether there is only a single God Bug or multiple ones.
- "You will know the name of God, the one true god - Behemecoatyl. Brain of brains."
- —Sky Marshal Anoke.[src]
It is unknown how long the God Bug has existed and the United Citizens Federation did not even know of the creature's existence within the Arachnid hierarchy until recently. The first clues as to its existence came from a captured Brain Bug that remained within the Federation's custody and was being studied. Through his psychic talents, Sky Marshal Omar Anoke became influenced by its telepathic mind and learnt of the God Bug known as Behemecoatyl. His interaction with the Arachnid Brain Bug led him to revere the God Bug as a deity and developed a religion around it.
When Anoke's starship crashed onto the planet known as OM-1, he discovered that a large part of the planet was the God Bug. He declared it as the one true god, much to Holly Little's disbelief, who had mistakenly believed Anoke to be referring all the while to the Christian God, whom she worshiped. After traveling to a specific area on the planet's surface, Anoke, Lola Beck and Holly Little encountered the large head of the God Bug. The Sky Marshal pledged his worship of the creature and his desire to bring peace. Behemecoatyl, however, had a different concept of "peace", and devoured him in order to gain all of his knowledge of the Federation's military assets. It was still left unaware of the location of Sanctuary, as Anoke did not possess that information. Beck, however, did.
Before it could devour Beck and extract the location of Sanctuary, Johnny Rico arrived on the scene with a group of his M11 Babar Marauders who proceeded to wound the God Bug as well as devastate its army of Warrior Bugs. Rico managed to evacuate Beck, Little and his team to the ship in orbit where they determined the large mass of the God Bug. In order to combat this massive threat, the Fleet deployed their new Q bomb, which destroyed the entire planet.
According to the Federation, without the God Bug's guidance, the Arachnids would apparently lose the war. However, with the slightest chance that this may not have been the only God Bug in existence, this could also have made the Arachnid armies even angrier and more powerful than ever before, inciting them to fight far more violently and gruesomely. Another fatal factor that should be considered is that all the vital knowledge that Sky Marshal Omar Anoke contained at the time had been absorbed by the God Bug and may have been transmitted telepathically to many offworld Brain Bugs before the God Bug's death. The intelligence the Arachnids may have obtained could possibly be used against the Federation.
In either way, the possibilities where Airachnid armies taking more agressive movements after God Bug's death confirmed true, where one of the Queen bug intentionally allowing herself to be captured by Federation during Battle of Fort Casey instead normally killed herself like other Queen does to keep her existence in secret. She later overpowered Carl Jenkins's psychic power on her with her own's, and later hacked John A. Warden to prepare the all-out attack on Earth. Though the invasion failed by the destruction of the John A. Warden, it's turned out that it was not a perfect failure due to one of her children, a lone Warrior Bug, has escaped from the blast radius. Despite this, it would take a very long time to resume her plans due to it's breeding rate that far inferior than Queen does.