Breed has the ability to create trilobite-like parasites that become more dangerous in time, they emerge at about the size of a lemon from his orifices. The original Breed may have had greater control over his 'Bugs' or may have been able to release more of them at one time.
They are described as being like trilobites. Thanks to their small size they can lurk in spots where they can get access to orifices, sites of injury, or corpses. Then burrow inside, wait until the target is still and quiet for an hour or two, paralyze the target, and emit pheromones to call their fellows to them. They devour the target from the inside out, molt once or twice as they digest the fats and proteins they ate, then find a new target. In a process that takes one to two weeks, depending on the availability of food sources, the creatures will reach the size of a full-grown human being. After this they’ll do two or three major molts with big physical changes, gaining some natural weapons, including a shotgun spit that releases pellets that dissolve as a flesh-melting acid.
Despite their insectoid appearance, they're unable to be sensed or controlled by Weaver.
They are sentient but not sapient, ignoring hard targets and going after the more prone prey. They feed exclusively on humans, but they would attack non-edible targets to remove a threat.
↑Breed Creates small lifeforms that inhabit corpses, grow and become more dangerous over time/after eating Slaughterhouse 9 Master - ParahumanList, Bolded edit by Wildbow
↑ 3.03.13.23.3“For now,” I answered Rifle. “They start off the size of a lemon, lurk in spots where they can get access to orifices or sites of injury, or like you see here, corpses. Inside beer bottles, in toilet bowls, bedcovers, on the underside of kitchen tables, even inside food. Then they burrow inside, wait until the target is still and quiet for an hour or two, paralyze the target, and emit pheromones to call others of their kind to them. They devour the target from the inside out, molt once or twice as they digest the fats and proteins they ate, then find a new target. It’s a process that takes a week to two weeks, depending on the availability of food sources.”
I could see Getaway shift position, folding his hands behind his back, as if he could shield his rear end. His mouth had shut into a firm line.
His nose was still unprotected, I noted.
Even Rachel seemed a little concerned. She glanced at her dog.
“They aren’t a danger to us,” I said. “Probably. They choose easier targets over harder ones, and there are enough corpses around here that we aren’t worth the trouble. What we should worry about is the later stages. When they’re about the size of a full-grown human being, they’ll do two or three major molts with big physical changes, gaining some natural weapons, including a pellet-spit that kind of acts like a shotgun blast with fragments that dissolve into flesh-melting acid.”
“Read his file,” I answered.
“Shouldn’t we kill them before they get big?” Foil asked.
“Not worth the time it would take to track them down,” I said. “We don’t have any strong offensive powers, they’re durable against stuff like conventional ammunition and physical blows, and he generally produces about nine or ten per day.” - Excerpt from Sting 26.1
↑Though it’s somewhat justified in this instance as they don’t retain their full memories – only cobbled-together personalities and histories. - Comment by Wildbow in Sting 26.3
↑The entity observed the ongoing conflict. No less than five seconds after it had been trapped, two figures had emerged from a doorway between worlds. The entity could see the paths forming, trace them back to the source. Another world, a living world without a shard occupying it.
They engaged the eight with their own perception abilities, intervening to assist a group of others. As a pair, they opened fire with guns, then waded into hand to hand combat.
↑druxilitch I think the S9!Taylor fic handles this pretty well: allow the parasites to inhabit and feed on cow carcasses or other large mammals that are commonly farmed. I think that if the parasites themselves could be trained and controlled by people other than their creator, they would make pretty good guard dogs and stuff. You could also maybe harvest them for resources.
↑I wasn’t the only one. Crucible’s forcefield shorted out. Clockblocker had been in the midst of reaching for Breed-bugs to lock down, and found himself only giving them easier access in climbing up his arms.
The Mannequin staggered back, tripping on the stairs. Just a little less coordinated.
Still, it wasn’t useful. One dog was entirely disabled, crawling with countless Breed-parasites. Only the fact that it clenched its jaw kept them from getting in its mouth, but its nose- - Excerpt from Sting 26.3
↑Her eyes tracked the rows and columns of incubation chambers. They weren’t her field either. A different row for each member of the Slaughterhouse Nine, past or present.
There were ten of each in various glass chambers. The original members. - Excerpt from Interlude 25
↑Shit. My bugs were so useless here. I couldn’t go after the Breeds until I knew which of the people in the building were them. The original Breed had died when someone had hit a building with an incendiary missile, and the bugs had stopped appearing. He wasn’t altered in appearance. For all respects, he was just an ordinary man.