The Army of Lice first appeared on Muffy's head and quickly made their plans to spread throughout the entire school. Although Muffy was ordered home after the Nurse confirmed she had them, the Lice continued to spread as Francine put on Muffy's hat which she dropped on the floor, so they spread to her hair as well. They continued to spread as other students fondled with Muffy's hat before being told by the Nurse not to wear anybody else's clothes due to the infestation, and so the Army of Lice spread rapidly and even began appearing the hair of the teachers.
Soon the Army of Lice had spread so far and wide that the kids' parents were forced to take measures at home to keep them from getting beyond the school. The kids had to be checked everyday to see if the infestation was still ongoing, and those with longer hair like Francine and Muffy even cut their hair short to stop them. The only one unaffected by the Lice was Buster, who's lack of personal hygiene made his hair too disgusting for the lices to reside in.
Though the Army of Lice had spread far, eventually the kids were able to beat them back and eventually only the General was still alive. In a last bid to rebuild his Army of Lice, he tried to jump to Buster from George's head, only to fall to the floor of the school where he was stepped on by the kids.