Marie-Noelle Robert, Associated Press
Ruxandra Donose, left, and Daniel Okulitch perform in a scene of "The Fly" in Paris.

PARIS — Be afraid, be very afraid: David Cronenberg's 1986 horror flick, "The Fly," has undergone a bizarre metamorphosis. It's now an opera.

The new incarnation, with tenor Placido Domingo conducting a score by Oscar-winning composer Howard Shore ("The Lord of the Rings"), isn't as gory as the movie. Audiences will be spared close-ups of the title character's fingernails falling off as he makes the transition from mild-mannered scientist to giant insect.

Still, for an opera, it's pretty scary — even if there are touches of dark humor. Giggles broke out among those invited to Monday's dress rehearsal when a mezzo-soprano belted out the film's catchphrase: "Be afraid. Be very afraid."

Cronenberg, who is directing the opera, wasn't sure what effect it would have.

"Someone's 6-year-old said, after seeing one of our rehearsals, that she thought she would have to sleep with her parents for a while," he told reporters. "So I guess it's working."

The opera will have its world premiere Wednesday at Paris' Theatre du Chatelet and its U.S. premiere Sept. 7 at the Los Angeles Opera.

Shore, a childhood friend of Cronenberg's who also wrote the film's original music, said he started picturing "The Fly" as an opera as soon as the movie was released.

He said he sampled only two themes from his 1986 work.

"I love the characters," Shore said. "I wanted to write for a drama that I was familiar with, and that I had a certain inside view of."

Reporters pressed Domingo on what attracted him to the story of star-crossed lovers, one of whom learns to regurgitate digestive fluids onto his food like houseflies do.

"Why not?" he said. "I couldn't resist."

The libretto by David Henry Hwang ("M. Butterfly") has all the elements needed for good opera: a love story, a transformation, tragedy and death, not to mention a large dose of melodrama.

The plot sticks to the same basic lines as the film, which starred Geena Davis and Jeff Goldblum. Reporter Veronica Quaife falls for eccentric scientist Seth Brundle at a reception. He takes her home to see his creation, a machine that can teleport objects from one place to another.

One drunken night, Brundle climbs into the machine. It works perfectly, with a catch: a housefly buzzed into the machine with him.

Overall, the opera has a very different feel. The setting has been changed to 1950s America, which somehow seems more operatic than the 1980s.

As Brundle, bass-baritone Daniel Okulitch has the unenviable task of performing arias in his birthday suit as he climbs in and out of the teleport machine. (Mezzo-soprano Ruxandra Donose is Quaife.)

The retro set design is evocative of 1950s horror flicks. And there's something thrilling about the old-school special effects — terrifically gruesome costumes, a singing teleport machine and a giant fly scaling an opera set.

"It is in some ways a translation of the movie to the stage," Cronenberg said. "But it's its own creature."