Really, it's getting so people can't go out alone in the swamps at midnight in a rickety old boat without feeling, you know, a little nervous. This has been especially true ever since vampire bats moved in next door and insisted upon swooping down on people, draining them of all their blood. You wouldn't think a little bat could hold all of a human being's blood, would you? Well, obviously they're just doing it to be mean.

The awkward situation leads to a number of agitated encounters that go like this: "Flutterflutterflutter." "What was that?" "What was what?" "Flutterflutterflutter -- Screeeech!" "Aaaaaaaghhhh!" And the next thing you know, the bats can chalk up two more victims and flutter on to the next ones.

That's essentially the plot of "Vampire Bats," this week's descriptively titled CBS Sunday night movie, at 9 on Channel 9. It was whipped up by the creative team (let's give them the benefit of the doubt) behind "Locusts." In case "Locusts" has slipped your mind, two of its cast members, Lucy Lawless and Dylan Neal, drop by to re-create their roles of husband-and-wife ecology professors Maddy Rierdon and Dan Dryer. Maybe that will refresh your memory!

Obviously the winsome twosome have a new environmental nightmare on their hands, a hideous mutation caused, of course, by a negligent corporation's reckless pollution. The film happens to take place in Louisiana, but has nothing to do with hurricanes like the one that struck that state, among others, earlier this year. No hurricanes, just bats. Bats, bats, bats, bats, bats.

The film adheres to a time-tested horror formula: Make sure that many of the people in harm's way are nubile teenagers. It's even mentioned in "Vampire Bats" that the area is suffering from a heat wave, all the better to justify the teenagers prancing and dancing in minimal amounts of attire. However, the film does not open with the cliched scene in which a boy and girl are out spooning and frolicking, hear a strange noise, dismiss it as the wind and go back about their business -- only to be attacked by a ghastly monstrous menace.

That scene is in the film, all right, but it occurs about halfway through. The opening scene this time is set at a fraternity party where some very naughty frat boys pour the drug Ecstasy (in powder form) into the punch bowl. That inspires wild abandon among the partygoers, one of whom wanders off into the bayou and soon enough is found lying quite dead in an ignominious puddle of swamp water.

As tradition demands, we don't see the bats the first time they attack. Instead, we see the victim from the bats' point of view. This, by the way, is one of the problems with trying to stretch a horror movie into a weekly series, as a few of the new fall shows (such as NBC's "Surface") do. Instead of waiting 20 or 30 minutes to see the monster, as in such movies through the ages, viewers have to wait weeks or even months before the unspeakable beastie makes a recognizable appearance.

Luckily for the Louisiana locals in the CBS movie, Maddy Rierdon has a PhD in animal behavioral biology, and you don't run into one of those every day. She and her hubby discover that the flying fiends with the bright yellow eyes are "not your everyday vampire bats." Good heavens, wouldn't everyday vampire bats be enough? Apparently not, because these have two sets of jaws, or something, and rabies, and insatiable appetites, and a maniacal lust to kill, kill, kill!

It would be hard to do a movie about these ugly airborne creatures, even the non-vampirical sort, and not have it be unnerving, because everybody with any sense is scared to bits of bats. Even if many elements of "Vampire Bats" seem, to say the least, familiar, director Eric Bross and writer Doug Prochilo still deliver some darn good frights, and since the "CSI" shows have established liberal new standards in how much gore can be shown on TV, the film is discomfortingly explicit about the damage the filthy creatures do.

These bats mean business, baby.

The film's other virtue includes a cast that is nothing if not eclectic. Maddy's meddling sister-in-law is played by the comedian Brett Butler, who -- though it's hard to remember, and even hard to believe -- briefly had a hit sitcom on ABC ("Grace Under Fire") several years ago. Craig Ferguson, the amiably affable and affably amiable host of CBS's rejuvenated "Late Late Show," has a bit part as a fisherman who goes to the wrong place on the wrong night. The bats do not discriminate and thus find Scottish blood as delicious as any other kind.

And Timothy Bottoms, still boyish after all these years, plays the town's mayor, who, like the mayor in "Jaws," wants everybody to keep calm and not go batty just because a few unfortunate souls have died horribly violent deaths. (One other detail stands out and is never accounted for: Maddy drives a Caddy, and not just any Cadillac but a big huge yellow luxury liner whose vintage is hard to determine. Awesome.)

The twisty "surprise" ending is awfully contrived, designed to put Maddy in mortal jeopardy at the last minute, but for the most part, this is, on its own limited and playful terms, a satisfying little shocker. Rabid and bloodthirsty vampire bats may prove inadequate at luring viewers away from rabid and bloodthirsty desperate housewives (in the show of the same name on ABC), but the frisky little fellers put up a helluva fight.

Vampire Bats (two hours) airs tomorrow at 9 on Channel 9.

Lucy Lawless, center, reprises her "Locusts" role as the biologist with a penchant for creepy creatures.