They look like mutant flies and sound like Charlie's Angels on helium. "Nobody invades Earth without a fight!" squeaks Blossom, the redhead, as the three cartoon kindergartners prepare to battle an invading army of aliens disguised as broccoli.

"We got to eat 'em to beat 'em!" they cry. Chomp chomp chomp.

Pow! Blam! Get those evil broccoli heads! The other kids of Townsville pour cheese sauce on the marauders and munch them down. Those darned hypnotransmitters implanted in their parents are destroyed! Bye-bye, bad guys!

Once again the day is saved by the Powerpuff Girls!

"The Powerpuff Girls" is the latest Cartoon Network hit to infiltrate the ephemeral youth market. They are big, very big. Even if you're not impressed with their audience of more than 2 million, or the CD that was at the top of both the children's and the college charts in Billboard, or the merchandising licenses expected ultimately to gross more than $350 million, you might have encountered one sure measure of their popularity. On Halloween, streets were full of pint-size imitators who, when asked their costume's identity, would confide, "I'm a Powewpuff Giwl."

Teenage girls like to mimic the squeaky baby voices of Blossom, Bubbles and Buttercup, the crime-fighting cuties. College kids appreciate the puns and pop culture allusions--like the episode called "Boogie Frights," and the time the people of Townsville were forced to disco-dance to near-fatal exhaustion. And the target audience--the 2-to-11-year-olds--has surprised everyone by being predominantly male.

To say that the Powerpuffs are a feminist answer to the Power Rangers or the Teenage Mutant Ninja Turtles would be an overstatement. Nonetheless, it is unusual to have girls in the superhero seat, driving the action and landing the blams. A small change in the pop culture, perhaps, but noteworthy.

"I just liked the contrast of cute characters being strong and tough," says creator Craig McCracken, 29. He designed the show originally for his film requirement at California Institute of the Arts. He called that first one "The Whoop-[rear end] Girls," a name that was changed for television in 1998. While he admits to being a pretty liberal guy, with an artistic family and a feminist girlfriend, his inspiration was simply to find "a fun idea" or "a cool concept," not to serve up role models for a new generation.

The age spread of the show's audience can be seen in Cartoon Network scheduling; there are half-hour shows most days from early afternoon to late at night. You have to assume that most 5-year-olds are not watching at, say, 11 p.m.

According to the story line, the tykettes were created by Professor Utonium, a genetic engineer who wanted to concoct three perfect little girls. To the traditional recipe of sugar, spice and everything nice he added "Chemical X," which gives them superpowers like the ability to fly, to see with "microscopic vision" and to pack a wallop with their tiny fists. Pow! They attend kindergarten at Pokey Oaks Elementary but always seem to be getting called out of class to fight evil. The bad guys are also big stars: Mojo Jojo, Him, Roach Coach, the Amoeba Boys and Fuzzy Lumpkins.

Each of the girls has an identity, but it's hard for a novice to tell them apart. Blossom wears a red bow and is the leader. Bubbles is blond and goofy. And Buttercup, the brunette, is scrappy, a "quick-fisted fighter who likes to strike first and ask questions later." The stories tend to unfold rapidly (each one runs 11 minutes) and always end happily. Holding evil at bay is not always accomplished through violence; sometimes guile and cleverness play a role.

The design aesthetic is a clash between blinding primary colors and sappy pink heart logos, sort of like Barbie living in a large box of Crayolas. There are cartoon cliches like missing teeth and Band-Aids on villains and a square head for upright Professor Utonium, and slightly sophisticated jokes (a brief homage to "Spinal Tap" in one episode, for example). The inevitable Web sites discussing the PPG--as they are called--proliferate, with reviews of each episode, the blunt assessments of the anonymous.

"Just when you thought it was safe to stop watching, Craig and crew come up with two new brilliant Powerpuff episodes," wrote one correspondent on Coldbacon.com. "Like most great art, we probably won't really appreciate it until after Craig is dead."

The writer went on to praise the dream sequence in "Dream Scheme" as "a Pink Floyd rock laser show, 'Alice in Wonderland,' and Alfred Hitchcock all in one fruit roll-up."

"I don't write for 6-year-olds," McCracken says. "I write for myself." Of course, he goes on to say, most cartoonists are 6-year-olds at heart.

He's also into music and has taken pains to marry the show to hip sounds. The compilation CD "Heroes & Villains" has music "inspired" by the Powerpuff Girls, by Devo, the Apples in Stereo and Bis. In addition to its success in the kiddie and college markets, it was at the top of Billboard's Soundtrack chart for eight weeks last summer.

Following in the tradition of the Rugrats, etc., a PPG feature film is already in process for release in 2002. McCracken doesn't want to reveal much of the plot. "It's going back to little girls being superheroes," he says. "There may be a new audience out there that doesn't have cable and hasn't seen the show."

If you've missed them before, you won't be able to escape them for long. Delta Air Lines has painted the Girls on a 737 jet wing, and the Subway restaurant chain offered a PPG kid's meal this fall. Future landfills will contain acres of PPG backpacks, bedding, birthday napkins and sundry other junk emblazoned with the bulbous eyes of the power sisters. Is that immortality or what?

"I am 100 percent surprised at the success of show," McCracken said. "I thought maybe college kids would like it, that it might be one of those cult hits that years later they'd say, 'Hey, you remember the Powerpuff Girls?' I'm in total shock."