Saoirse Ronan doesn't just play "The Host" in director Andrew Niccol's upcoming alien invasion drama — she's one in real life too! The actress, along with co-star Max Irons, recently welcomed MTV News to their Albuquerque, New Mexico, set, where we got a behind-the-scenes look at the film.

Based on the best-selling novel by Stephenie Meyer, "The Host" tells the story of alien soul Wanderer, who has taken up residence in Earthling Melanie Stryder's body. But Melanie hasn't given up complete control of her mind, leaving the two in an uneasy alliance as they share one form. The film stars Ronan in the dual role of Melanie/Wanderer and Irons as Melanie's love interest Jared. The romantic leads have an easy chemistry offscreen too, evidenced by the playful manner in which they answered a handful of fan-submitted Twitter questions posed by MTV News' Josh Horowitz.

First up: "If you were a soul, whose body would you inhabit?"

It took Ronan and Irons a few moments of contemplation before giving surprisingly in-sync answers. "Beyoncé, probably," Ronan said. And once Irons got confirmation that he would indeed receive the talents of whomever he possessed, he offered up his choice of Beyoncé's hubby, Jay-Z.

The next question was specifically for Irons: "Have you ever mispronounced Saoirse's name?"

Irons can thank his mama for this answer.

"That's a good question," he began. "I wish I had, but I don't think I have."

"His mum is Irish, so he does not have an excuse," Ronan said with a grin.

And then there was this last question, which elicited a bit of an unexpected response from Irons regarding a very particular phobia: "What's something embarrassing or unexpected that's happened to you on set?"

"Well, Jake [Abel] and I were going to pull a prank on Max, but that hasn't worked out yet," Ronan revealed. "Come on. Come on," Irons prodded.

"I'm going to ruin it now because we were going to do it in the last week, but we're not going to be able to do it. We have these bugs. Well, [Abel] has them. He found them in New Orleans, and he was going to put them in your trailer, and it was his idea. He told me about it, and I just agreed."

And just to add an extra wrinkle to this already awesome prank, as it turns out, Abel is Irons' unofficial exterminator.

"See, the other day, I was in my trailer and there was something in the trash can," Irons said. "I was convinced it was a moth, and I had to go out of the trailer, because I cannot stand that kind of thing, and get Jake. So I trusted him. I went to him in my hour of need."

When Ronan clarified that they were going to plant a bug and not a moth, which is really just like a butterfly, Irons demurred.

"It's nothing like a butterfly. In fact, when they get too close ..."

"What, they'll flutter?" Ronan asked, adding, "It does kind of freak me out though when a butterfly sticks your hand."

So there you have it. If you want to freak out the young stars of "The Host," just wrangle up a few sticky butterflies.

Check out everything we've got on "The Host."

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