Even casual fans of the vampire genre know that an undead bloodsucker can enter a room only after's he's been invited. At the very least, you have to admire his manners. And aficionados of animal programming know that the obnoxious pets rescued and re-educated on shows like "Dog Whisperer" and "My Cat From Hell" are often considered members of the family.

So it's a little terrifying that some of the most dangerous creatures of all never wait for an invitation -- and that some have been living with us for years. Now in its third gut-wrenching season, "Monsters Inside Me" (8 p.m., Animal Planet) explores those microscopic bugs that dwell inside every human being. Most of the time, such bacteria help us digest food and keep our inner life in balance. But, to paraphrase the late disco queen Donna Summer, when they're bad, they're oh so bad!

The first installment in this queasy season sports a suitably tabloid title: "My Child Will Only Eat Cat Food." Not to give too much away, but the Friskies-loving tyke may be suffering from a deadly elevation in white blood cells arising from the activities of a deadly roundworm. And this child doesn't have nine lives.

Week after week, "Mon sters Inside Me" exposes deadly parasites that live inside people, causing extreme pain and devouring flesh inside the body and on the skin's surface, which drives them to

bizarre behavior and takes at least one subject to the brink of suicide.

Bon appetit!

---If that wasn't enough to make you worry, "Forecast: Disaster" (National Geographic, TV-14) looks at extreme,


disturbing events captured on film, ranging from "Deadly Quakes" (9 p.m.) to "Deadly Avalanches" (10 p.m.). Host Ben Fogle likes to deal with extreme situations on his own terms. He's participated in a 160-mile auto race across the Sahara Desert and engaged in a foot race to the South Pole.

---The EPIX network celebrates a half century of James Bond with a 24-hour Bond movie marathon and the premiere of the documentary "Everything or Nothing: The Untold Story of 007" (8 p.m.).

---The last day of school proves eventful in the 1993 coming-of-age comedy "Dazed and Confused" (9:35 p.m., Encore), sporting a terrific young cast that includes Jason London, Milla Jovovich, Parker Posey and Matthew McConaughey.

---The 2007 comedy "Walk Hard: The Dewey Cox Story" (9 p.m., Fox Movie Channel) lampoons the pieties of big-screen musical biographies and skewers a virtual pantheon of rock legends. John C. Reilly acquits himself well as a singer on the catchy soundtrack.


---The new series "John Fugel sang: So That Happened" (6 p.m. and 9 p.m., Current) reviews the past week in popular culture.

---A serial arsonist strikes again on "CSI: NY" (8 p.m., CBS, TV-14).

---On two episodes of "Grimm" (NBC, TV-14), a church robbery (8 p.m., r), unhappy tidings (9 p.m.).

---Major League Baseball Wild Card Games (TBS): National League: St. Louis at Atlanta, 5:07 p.m.; American League: Baltimore at Texas, 8:37 p.m.

---A major strike and a grievous loss on "Bering Sea Gold: Under the Ice" (9 p.m., Discovery, TV-14).

---A letter from prison proves

illuminating on "Made in Jersey" (9 p.m., CBS, TV-PG).

---The team returns to the Harvard lab on "Fringe" (9 p.m., Fox, TV-14).

---A case of domestic violence is anything but routine on "Blue Bloods" (10 p.m., CBS, TV-14).

---Dragging rivers for driftwood provides firewood on "Yukon Men" (10 p.m., Discovery, TV-PG).

---A budget meltdown forces Kane to compromise with his

enemies on "Boss" (9 p.m., Starz, TV-MA).


Teens terrorize a family trying to start a new life in a desert town in the 1967 shocker "Hot Rods to Hell" (4:15 a.m., TCM), starring Dana Andrews, Jeanne Crain and Mimsy Farmer.


---Boot camp beckons on "The X Factor" (8 p.m., Fox, r, TV-14).

---A chicken dip evokes an

emotional response on "Shark Tank" (8 p.m., ABC, TV-PG).

---Motel photo shoot on "Amer- ica's Next Top Model" (8 p.m., CW, TV-14).

---George comes clean on "Hart of Dixie" (9 p.m., CW, r, TV-PG).


---Kristin Chenoweth, Brody

Stevens, Sarah Colonna and Brad Wollack appear on "Chelsea Lately" (11 p.m., E!, r).

---Billy Crystal and the Wall-

flowers appear on "Late Show With David Letterman" (11:35 p.m., CBS).

---Jay Leno welcomes Colin Farrell, Medal of Honor recipient Dakota Meyer and the Hives on "The To night Show" (11:35 p.m., NBC).

---Katie Couric, Jerry Trainor and Dom Irrera visit "Late Night With Jimmy Fallon" (12:35 a.m., NBC).

---Craig Ferguson hosts Dr. Sanjay Gupta and Ginnifer Goodwin on "The Late Late Show" (12:35 a.m., CBS).

Kevin McDonough can be reached at kevin.tvguy@gmail.com.