Flies that had burrowed into a rotting corpse swarmed and infested a Hollywood studio, lingering for days. A sheet covered the mutilated face of an actress, hiding her from children as her wheelchair was navigated through the hallways of a school. The demonic Infantata monster creeped out from a trailer, shocking a nearby production assistant.

These are not scenes from FX’s hit series, “American Horror Story”…these are true stories from the crew that works to create the show. Horror and haunt convention ScareLA’s last panel in Pasadena last weekend featured the crew behind the visual stylings of “American Horror Story.” The panel was made up of make-up artists Eryn Krueger Mekash, Kim Ayers and Mike Mekash, cinematographer Michael Goi, and visual effects artist Jason Piccioni. Even Twisty the Clown from last season’s “Freakshow” made an appearance: a model of his likeness loomed behind the panelists as they spoke about the show.

This panel, moderated by ScareLA executive producer Lora Ivanova, was originally billed as an insightful look into the world of creating monsters—and where panel attendees could pick up tips for future Halloween costumes. But it actually expanded into a much broader exploration of the effort and creative power it takes to create the visually unique worlds of the series.

As “Horror Story” fans know, each season of the television series is its own, stand-alone mini-series with a new setting, new characters and new plotlines. The show has been recognized for its achievements in visual effects, with its last season, titled “Freakshow,” earning 19 Emmy nominations, among them nods for best make-up, best prosthetic make-up, best cinematography and best special visual effects.

Eryn Mekash said executive producer Ryan Murphy aims to create a particular style for the series that takes familiar tropes and presents them to the audience in ways they have never seen them before.

For example, it took the crew two months to decide on how the alien in season two’s “Asylum” walked and moved—it couldn’t move too much like a spider or a man (too familiar). And the alien’s movements rarely even ended up on camera in the final product.

“The bottom line is we want to create something that no one has seen before, that definitely has never been seen on TV before,” Goi said.

Another notable challenge in creating the show involved filming last season’s Siamese twin characters, Bette and Dotte, played by Sarah Paulson. Goi said it originally took eight hours to film a single scene. He eventually figured out a way to shoot all of Paulson’s angles at once, using five cameras, to speed up the process.

“It was amazing,” Eryn Mekash said.

But these challenges and innovative choices are a large part of what draws these creative employees to the series, Eryn Mekash said.

“It’s never boring,” she said. “There’s always something new to be inventing.”

They also shared stories about the pranks and mishaps that occur when shooting some of the grisliest scenes in the series. Actress Chloe Sevigny, who becomes a mutilated amputee in season two’s “Asylum,” was covered with a sheet while moving around off-set when the scene was filmed at a school. This is partially because the crew always hides their make-up work from the public until the series debuts–but this particular case was also exacerbated by the fact that the school they were filming in was actually in session that day.

The late Ben Woolf, honored at the panel as, in Eryn Mekash’s words, “a beautiful human being,” spent much of his time on set for season one’s “Murder House” jumping out at cast and crew members off-set in his Infantata costume, surprising them and laughing.

Other notable stories include how using real flies to shoot a scene with a rotting corpse in Murder House resulted in a fly infestation at Paramount studios for at least a week. Actor Evan Peters spent much of his time off-set for Freakshow practicing holding his fingers together like claws to prepare for his role as “Lobster Boy.” And when Stevie Nicks first arrived on set for her appearance in season three’s “Coven,” Mike Mekash recalled that he immediately freaked her out when he showed her the prop of Kathy Bates’ severed head.

“You try to have fun,” Mike Mekash said about working on the show.

As fun as it is for these self-professed horror lovers to have made a career inventing strange, creepy characters and worlds, the panel members also discussed moments when the show has disturbed even its creators.

Eryn Mekash, who grew up on ’80s horror films like “The Changeling,” said that throwbacks to the movies that frightened her as a child have pushed her buttons. Piccioni remembers turning away from the monitor while reviewing Murder House basement sequences involving baby parts in jars.

But at the end of the day, the crew said that they love what they do.

“My passion has transformed into career for thirty years now,” Eryn Mekash said.

The panel also included words of advice for those interested in joining the industry. Panelists agreed that one of the most key points in a creative career is to allow for compromise, and to expect that not everything will go exactly as planned during filming.

“My entire career is based on making total compromise look like intentional style,” Goi said.

He also suggested that up-and-coming artists appreciate the job interview process, and use it as a platform to show their unique visions and ideas.

“It’s the one pure time that you can express artistically what you can do for the project,” Goi said.

He laughed and added that the job interview is not yet the time for artists to worry about how to execute their ideas.

“Worry after you get the job,” he said.

As for the next installment in the franchise, season four’s “Hotel,” the panelists only teased that it was going to be full of surprises.

“It’s so scary and so creepy and so gross,” Eryn Mekash said. “You guys are going to love it.”

She also shared that although Lady Gaga will be joining the cast, unlike in last season’s Freakshow, season four will not include musical performances.

“Although with Ryan [Murphy] you never know,” Eryn Mekash said.

When asked which horror tropes they’d like to see tackled by the series in the future, Eryn Mekash considered werewolves, Mike Mekash suggested a Charles Manson-esque cult, but Goi earned applause with his unique response: “I think the scariest thing in the world is the American political process.”

But ultimately, Eryn Mekash said, the only way to learn what the show has in store next is to keep watching.

“Tune in for more dirty, cool, gross stuff,” she said.