This season's TV series are chock-full of crawly bugs, ghosts with some serious revenge issues, disturbingly creative serial attackers and aliens that do not come in peace.

"I don't think this is new," said Robert Singer, executive producer of "Supernatural" on the WB network. "I think people have been going to scary movies for as long as filmed entertainment has been on. And even before that with stage plays. It goes back to people telling ghost stories around a campfire."

Shaun Cassidy, executive producer and creator of "Invasion" on ABC, agreed. "Fairy tales help kids process their demons. Scary stories exist for adults for the same reason."

The scary stories unfolding on TV this season follow some simple rules for success, including:

Using comedy: Hurley on "Lost" is a prime example of this. On "CSI," Grissom is always dropping one-liners before investigating a crime, and the brothers on "Supernatural" make a sport of the fake names they throw around: "Star Wars" and the band Metallica were recent inspirations.

"Humor saves the day," Cassidy said. "Even in their darkest hour, people are funny."

Singer likes to disarm his audience with humor and then hit them with a dose of horror.

Providing answers: The brains behind shows based in mystery know that eventually there has to be a payoff for the audience or a series can get tangled in its own mythology (see the final seasons of "The X Files").

"Lost," for example, kicked off this season by letting viewers know exactly what was down that blasted hatch. On "Invasion," Cassidy promises that many of the questions posed in the pilot episode will be answered soon.

Avoiding obvious plots: Playing with people's expectations and not succumbing to the cliches of the genre are part of the plan for many shows. "I think if we do subscribe to a convention of the genre, it's that we try to lull the audience into a sense of comfort and then spring (something horrific such as) the Carver on them," Shephard said.

Basing it in reality: In "Supernatural," Singer said, "one thing that we try to do is to ground all this in some sort of legend — something that, if you Googled it, you could find it." Take, for example, the Bloody Mary episode that explored the lore behind that creepy character.

Crime shows take a different approach. In "The Closer," Shephard said, "there are no monsters out there. ... these are crimes that any one of us could have committed if we were pushed."