"Ratty red-brown fur smeared in shit. Fingernails curved like snail shells. Teeth set in gums like maggots in a side of beef. Crusty black eyes, dribbling snot and spit. Its behavior is self-evident, and all are thankful that they cannot work in unison for more than a few hours before the backstabbing begins."
Cacopithicus is everything bad about great apes with none of the good parts. A dead end of amygdala-dominated brains with stunted neocortexes flooded with testosterone. The world of the cacopithicus is divided solely into things to murder, things to rape, things to cause pain to, things to run away from, and rocks.
The scariest part, though, is not the apes in particular. It's how easy the thoughts of normal, everyday, mostly-decent people start to slip when they're nearby. When cacopithicus shows up, someone is bound to say "well, maybe we should get rid of them."
They're right, of course. It's not safe to be out of doors when a cacopithicus mob is around. If it's just slaughtered livestock and damaged property everyone's off lucky. So everyone grabs their pitchforks and scythes and hunting muskets and grandpa's old cavalry saber and heads off to the woods and some people who come back come to the horrible realization that there is a distressingly small buffer zone between cacopithicus and human. Same branch of the same tree, just a few twigs over. There's nothing magical or ineffable about them. They're just apes. Like us.
So the village gets rid of the cacopithici and all is well for a while. But some of those people think "wait a minute...those apes are scarily like us. And you know, maybe there are some people who are scarily like them. Those strange folk over on the other side of the mountain, the ones who talk all weird and fought us back during the war...sometimes those folk act like those damn dirty apes."
The meme must be stopped there. There needs to be the good sense and common decency that the people on the other side of the mountain are not cacopithicus. For whatever evils they exercise they are not cacopithicus. If the thought is not stopped there...it never ends well.
Cacopithicus are no different from apes carrying disease, stat-wise. The societal danger does not have statistics. If they are not solitary, they will attack in mobs of six to twenty. They will break everything in as horrible a means as they can, vomit and shit over everything, and flee when clearly outmatched.
Many thanks to Edrick, via Discord, who showed me that picture and encouraged the creation of this post.