The Annihilation Wave is a insectoid species from another universe known as the Negative Zone lead by the Annihilus Alpha male and his queens.
The species is a mutation from spores accidentally seeded by the Tyannans on the volcanic planet of Arthros. Through rapid mutations, the spores matured into an insectoid lifeform which eventually evolved to sentience. The species is highly diversified into specialised subspecies. The most advanced subspecies can, upon their death, release a pod containing a nymph-like clone possessing their memories.
One of them, finding the wreckage of the Tyannan ship that had crash-landed on its world, saw its intelligence enhanced by the use of a Tyannan knowledge transference helmet and was able to master the Tyannan technology and perfect it. Obsessed with survival, the paranoid creature, who came to be known as Annihilus, set out to destroy any other living being he viewed as a possible threat to his existence. Annihilus used his newly acquired power to dominate all other lifeforms on Arthros, and plotted to either conquer or destroy the neighboring worlds in the Negative Zone.
After raiding vast areas of the Negative zone, Annihilus lead his annihilation wave in our universe in 2006, claiming that as the universe is expanding into areas of the Negative Zone, making the universe now rightfully his territory. He wrecked havok in the Andromeda Galaxy before being stopped.
Source: Marvel universe: Fantastic Four Annual #6 (1968), Created by Stan Lee and Jack Kirby