MathBench > Population Dynamics

Mystery of the Missing Housefly

The mystery begins


It had been a long night of too much gin and too little tonic. Seemed like the whole world was buzzing. And then she walked in. She was fly. Literally. One eye fixed on me like a golden jewel that men killed over, while the other fixed on my potato salad.

“How can I help you, Ms. …”

“Domestica,Musca Domestica.” She extended a delicate antennae. “I need you to locate these.”

She handed me photograph. It looked like a park bench, or maybe it was dung heap. It was hard to tell, because everything was covered with about a billion flies.

“Nice composition,” I said. “Who are they?”

“My relatives,” she replied trembling.

A typical housefly lives 6 weeks, and can produce 120 female offspring every 2 weeks. (There are also male offspring, but since they don't reproduce directly, its easier just to count the females).

By the ripe old age of 28 days, how many granddaughters should Ms. Domestica have?

(To make this problem interactive, turn on javascript!)

I think I have the answer: 14,400 granddaughters


Many facts about houseflies for this module are taken from "BUZZOFF! THE HOUSEFLY HAS MADE A PEST OF HIMSELF FOR 25 MILLION YEARS," by Anthony DeBartolo. You can find the original article here.