One becomes 10. Ten becomes 50. Fifty becomes...
That describes Philadelphia's age-old rat problem as much as it describes the complaints the city's health officials get about said rodents.
Like many of America's older cities, with miles of undergound corridors and alley ways, rats aren't hard to track down. But they are hard to control.
NBC10 Investigators found that workers with the Philadelphia Department of Public Health's Vector Control program are trying their best to keep up with the rodents.
"We'll respond to any complaint of rats," Ray Delaney of Vector Control said. "We'll bait any rat burrow we come across."
But with over 7,000 complaints of rats in the last two years — about 10 on average each day — it's less a war to win and more a challenge of containment.
"The city will never be out of rats," Delaney said.
Taking a walk around Rittenhouse Square with rodentologist Bobby Corrigan reveals the (somewhat) hidden world all around Philadelphia. He pointed out holes in walls and pavement.
"This species that's in Philadelphia loves sewers," Corrigan said. "They're protected all year round and stuff comes down to the sewers, food comes by. Water comes by."
He said the neverending battle is still worth fighting because a controlled population is better than an infestation.
"Rats can chew electrical cables and make holes in gas lines," Corrigan said. "They do cause fire or cause explosions when they knaw into gas lines. It's just not an animal we want close to us."
Anyone can call Philadelphia's Rat Complaint Hotline (215) 685-9000. The Vector Control program can be found online here.