Fallout 3 - Wasteland Survival Guide. chapter 2-Mole Rat Repellant. Moira wants the Lone Wanderer to test out her new mole-rat repellent, which she has placed on the end of a stick, on some mole rats. Three is enough to finish the quest, while ten is preferred for a more thorough test of the repellent. Contrary to the name, the mole rat repellent does not repel mole rats. Instead, it causes their heads to explode. One hit causes a delay of a few seconds, while two hits kill them instantly. Moira is not happy when she finds out.