Updated

Feces-stained walls, heaps of garbage and swarms of rats are the squalid conditions two Bronx parents allegedly raised their four children in.

“You had to do everything you could to not throw up,” a police source said of the putrid Kingsbridge Avenue apartment where the couple’s 5-year-old son was found alone amongst the filth Friday.

The crying tot was rescued by a horrified FedEx deliveryman who came by to get a signature on a package.

Once he got a glimpse of the repulsive pad where Charlotte Lewis, 48, and husband Wilfred Lewis, 59, lived, he ran to get the nearest authorities, police sources said.

apt exterior

In the hallway outside the family's apartment, 2J. (Christopher Sadowski)

The mom, a nurse at Montefiore Medical Center, was arrested at work, while the dad, an adjunct professor at TCI College of Technology and an MTA worker, surrendered to the 50th Precinct station house, sources said.

The family’s other children — two girls, 12 and 13, and a 15-year-old deaf boy — were in school at the time.

“I won’t leave him alone anymore,” the boy’s father tried to reassure cops after he was arrested for leaving the boy unsupervised, according to police sources. He also claimed his son was “self-sufficient.”

The parents were charged with endangering the welfare of a child and failure to exercise control of a minor.

The mother’s Facebook profile picture paints a wildly different story, showing her smiling with her kids in front of the Rockefeller Center Christmas Tree with a border that reads, “Live. Laugh. Love.” The children appear happy, well fed and clean.

One neighbor, however, had noticed the fetid conditions before.

“A couple of times they would leave the door open and I would always tell my boyfriend ‘Oh that house is kind of disgusting,’” Deanna Strom, 27, told The Post.

Among the rubble, police found hundreds of black flies, maggots and bedbugs and a completely empty refrigerator, police sources said.

The family had also been contacted by the Administration for Children’s Services multiple times, sources said.

Click here for more from The New York Post.