The Brood's civilization is based on insect societies such as the bees or ants consisting of a Hive-like lair. All Brood civilizations share strong telepathic bonds with their Queens, thus predicting no rebellions occurring against the Queens. The Broodlings do all the work and have an undying allegiance to their Queen, however each Queen do not share in a common interest.
There are a few different types of Brood. Starting with the Broodlings who are brown in color and have known to have transparent wings. Next up is the Queen, which is also brown in colour and have no wings. They give out the orders to the Broodlings to fulfill. The second last are referred to as "the Pure-Borns", they are the firstborn offspring which have had no exposure to other races, they are green in color and rather large.
Lastly, the Empress Brood which is also green in colour and extremely large, they are the supreme rulers of the Brood. Recently Phyla-Vell (the new Quasar) and Moondragon encountered and fought a newly discovered strain of the Brood species above the planet Dlaw-Neurg during the events of Annihilation: Conquest. Unlike its brethren the Brood had no eyes, a brown-colored heavily armored exoskeleton and silver-colored wings.
The Brood also possessed the ability to breath in space and was at the very least three times the size of a full-grown Brood Empress. The creature, as far as anyone can tell, was little more than a feral beast and was not raised in a Hive-mind culture like its cousins. Moondragon later deducted that the Brood (along with a sand-dwelling member of a previously undiscovered gargantuan insectoid species) were the guardians of a deserted palace Adam Warlock once lived in sitting in the sand dunes of Dlaw-Neurg and therefore were not actually natives of Dlaw-Neurg leaving the Brood's true origins open to speculation.
Recently, an unknown alien adversary of Kitty Pryde secretly infected her with an airborne virus that impregnated her with a microscopic Brood egg-sac, which made her body grow into that of a pregnant woman in her ninth month within a span of a few hours. It should be noted that these micro-Brood have been engineered to grow by consuming every last cell of their host from the inside-out and therefore must be removed before the Brood have a chance to grow out of control.
Originally, the Brood had a much softer, docile form. Having traveled to the past, Wolverine came across one in a S.H.I.E.L.D. research facility. Rescuing the creature from his confinement, it attacked Wolverine by trying to put a Brood embryo inside him. Wolverine countered by stabbing himself in the abdomen where the embryo was. The embryo died and the creature tried to attack him physically. Wolverine slew it with his adamantium claws. Coming across a monitor, Wolverine saw that the creature was part of a hive which adapted itself according to the damage the creature had sustained. It developed an exoskeleton and expanded its teeth and jaws. Wolverine realized he was reponsible for the evolution of the Brood into the savage creatures they were today.
The Brood was created by Chris Claremont, Dave Cockrum and Bob Wiacek in 1982 and first appeared in Uncanny X-Men # 155.
Major Story Arcs
The Brood Saga
Xavier and the X-Men are on a Shi'ar spaceship led by Lord Samedar and Araki. They tell the X-Men about Lilandra's kidnapping and their plan to invade Earth. The X-Men are opposed of course, so they head back to Earth and get Jarvis and Tigra to help. Deathbird and the Brood attack Corsair and Storm. The rest of the X-Men arrive to help them defeat the Brood, but Deathbird escapes and holds Xavier against his will.
All of the X-Men were infected by the Brood, except Carol Danvers. Wolverine's healing factor saved himself by purging the virus. He saved the rest of the X-Men except for Fang who became a Brood Warrior. While the X-Men leave, the Brood Queen realizes this and instructs the Queen embryo inside Cyclops to stop them. They find a dead Acanti prophet and recover the "Soul" inside of a crystalline object in his brain. The Brood find the X-Men and defeat them while they mutate into the Brood themselves. The Soul starts to get corrupted as well, and Wolverine tries to stop his teammates. Carol arrives and has a new appearance due to the Brood experimenting on her, and she releases the Soul. It cures the X-Men, crystallizes the Brood Queen, and destroys the Broodworld. X-Men, Lilandra and Lockheed escape, as well as some of the Brood escaping from the exploding planet.
One notable aspect of this story-line is when Storm is infected by the brood and heals herself by jettisoning into outer-space and becoming one with an Acanti being.
Age of Apocalypse
In this reality, the Brood possessed the Shi'ar who later encounter the Starjammers which included Cyclops and Havok's father, Christopher Summers. He ends up getting infected by the Brood. He later crashes on Earth and is later kept captive by Mr. Sinister. Christopher Summers later escapes the lab and meets up with his lost sons only to end up losing control to the Brood inside of him. He is then killed. In this reality another character infected was: Colleen Wing.
Annihilus and the Annihilation Wave (a race of insects) led an invasion and destroyed nearly all of the Brood species.
Planet Hulk (and World War Hulk)
In Planet Saakar, the Brood arrive and their Queen decides to mate with Miek, an insect king. They discover that Miek betrayed the Hulk, and the Queen and Hulk retaliate against Miek. The Earth Hive (an omni-consciousness of insects) decided to use Humbug to make the Queen infertile and kill the hivelings growing inside Humbug
The Brood in the Ultimate Verse are Danger Room programs. They later revealed to be creatures that originated from the Mindscape, where the Shadow King resides.