The movie opens with a worker coming up out of the old mine. He's an old-fashioned, independent miner, the kind that mines by flinging lit sticks of dynamite toward the mouth of the cave. But this old Scottish southern pirate miner becomes the first plump and tasty morsel of the giant, carnivorous, mutant mosquito.

As Anne McDonald, the former swimsuit model turned entomologist, collects the larvae of the new Brazilian Tiger Mosquito, she hears the commotion of drunk poachers, fishing with dynamite. She nearly becomes collateral damage as the temper-flaring forest ranger roars up to dispatch the poachers. But the poachers are not alone… the cousins of the poachers try to make Ranger Bob pay for his insolence. Bob uses his kung fu to dispatch them all.

Enter Philip Scrotack, the CEO of Scrotack Industries, one of the coldest villains ever to frost the silver screen. He and his accomplice, the sniveling Mayor Perry Butts, concoct a hellish plan to continue dumping toxic waste in the forest, in exchange for town improvements.

Deep in the forest, three campers stumble on a terrible sight. Barrels of green radioactive toxic waste, and a giant, hungry mosquito. It's lunchtime.

After rescuing a small animal trapped in the woods, Ranger Bob comes back to his cabin, to be met by ranger interns Susan and Bernie. They inform him of missing campers. Bob searches for them, but only finds skeletons. Then, he finds Anne the injured entomologist. She also found the mosquito, but escaped by the skin of her teeth.

Bob takes Anne to the town doctor, the wise and crotchety Old Doc Fodder. The Doc exhorts Bob to "find out what's going on in those woods."

A film crew, filming a new mosquito repellent commercial, are the next entrées of the bug. When Ranger Bob investigates, he comes face to face with the terrible toxic spawn.

Ranger Bob tells Sheriff Billy Roy Butts about the hideous, gigantic insect. Then Bob discovers the sheriff's horrible secret.

Sheriff Billy Roy goes to his brother, Mayor Perry Butts, who is unloading barrels of toxic waste for Scrotack. Together, they plan to do away with Ranger Bob before he uncovers the dark design of dumping.

As Bob and Anne rest in Bob's cabin, the place is invaded by dozens of Scrotack's ninjas. Bob must dispatch them using only his hands, feet, lamps, blankets, and beaver traps.

Bob and Anne learn of the dumpsite and the next scheduled shipment of ugly green waste. In enlisting the help of ranger intern Susan, we learn of Susan's terrible psychosis.

Narrowly escaping the pig-piling teamsters, Bob is rescued by Anne on her jetski. The teamsters chase them in their boats, but the exciting chase is interrupted by Mr. Mosquito and its punishing proboscis. This time, Anne isn't so lucky, and it swiftly swoops and grabs her, taking her back to it hive to feed it's larvae.

Ranger Bob with a single-minded purpose to rescue Anne, goes after the bug with a vengeance. But the sniveling Butts and the icy Scrotack are after him.

Can Bob rescue Anne? Can he escape Scrotack? How will he destroy the bug? And what monumental horror will happen to Butts and Scrotack?