As Taqwus said - stick the Maenads out in front of the real troops. Sure, they die fast - but in doing so, they act as a damage sink that soaks up arrows and lances from the opposing side.
In addition, the enemy accrues some fatigue (and possibly even some wounds) while butchering the maenads. That fatigue increases the chances of them missing your units, of your units hitting them, and of your troops hitting chinks in their armor.
In effect, you have to decide whether to get troops killed off that take gold and resources to build, or whether to allow free units that generate automatically to do the dying. Easy decision for me.
