The Missing Piece: How Mice Actually Decide Where to Live
This is the part that changed everything for Dr. Dunham.
Mice don't choose your home because it's dirty. They choose it because it smells safe.
Previous mice leave behind invisible pheromone trails in urine, in oils from their fur, in droppings that signal to other mice: this place has food, warmth, and shelter. Come here.
Killing the mouse doesn't erase the trail. The trail persists for months. New mice follow it. They enter through the same gaps. They nest in the same walls.
"This is what I missed for 22 years," Dr. Dunham says. "I was focused on the mouse. I should have been focused on the environment."
But here's the breakthrough:
Mice have two completely separate sensory systems for evaluating their environment. Their standard olfactory system what we think of as "smell." And a second, independent system called the trigeminal nerve pathway which detects chemical irritants and danger signals.
The trigeminal nerve is their emergency alarm. It overrides everything. When it fires, the mouse doesn't investigate. It doesn't adapt. It leaves.
"Every natural repellent on the market peppermint sprays, cedar sachets, single-oil pouches only targets the olfactory system," Dr. Dunham explains. "The mouse smells it. It's mildly annoyed. And within 3 to 5 days, it habituates completely. The scent becomes invisible."
That's why peppermint oil never works long-term. That's why cheap sachets fail. They're whispering into one ear while the other ear hears nothing.
"But when you hit BOTH systems simultaneously olfactory AND trigeminal with multiple compounds that each trigger a different type of alarm? The mouse cannot adapt. It's not one signal. It's system-wide overload. Every danger pathway fires at once."
The mouse doesn't die. It doesn't suffer. Its body simply says GO. And it goes.