Escargot, anyone? This Giant African Snail can literally eat you out of garden and home. Photo: USDA.

When some creepy, insidious, alien bug eats up your entire yard, you probably think it flew in, walked in, or crawled in by itself. But did you know that one of the most common ways evil pests invade is by hitching a ride with people? Here are 4 such pests identified by the U.S. Department of Agriculture as having the potential to wreak havoc in the South. They're either here already or itching to move in.

Scary, Gross Pest #1 -- The African Giant Snail (above) Reaching 8 inches long and 5 inches wide, this is one of the largest land snails in the world. It's the size of your fist. Right now, it's only in Florida, probably brought there as either somebody's pet or somebody's entrée (a really bad idea since it harbors a parasite that causes meningitis). But just because it's tropical doesn't mean it can't take cold. It could spread as far north as Maryland and as far west as California. One snail can lay up to 1,200 eggs a year.

Nervous yet? Then chew on this. In addition to having a ravenous appetite for more than 500 kinds of fruits, vegetables, and ornamental plants, your house is also on its menu. It enjoys a dessert of plaster and stucco. One portico wall coming up!

African giant snails are under federal quarantine in Florida. If you live there and spot one, put down the salt shaker and call this person immediately: Dr. Francisco Collazo-Mattei. 352-313-3060.

emNo, this ain't no hummingbird. It's a serial tree killer coming to your yard called the Emerald ash borer. Photo: USDA./em

Scary, Gross Pest #2 -- Emerald Ash Borer (above) The emerald ash borer is a beetle whose larvae bores into ash trees and kill them. It has killed millions since it first appeared in the Midwest about 10 years ago, probably hitching a ride from Asia in wood packing materials. It targets all species of ash, prime components of Eastern hardwood forests, including the venerable white ash (Fraxinus americana), from which Louisville Slugger bats are made.

No longer confined to the Midwest, the emerald ash borer is currently found in Kentucky, Maryland, Missouri, Tennessee, Virginia, West Virginia, and is southward bound. An infested tree starts dying from the top. Its riddled trunk looks like this.

emBuckshot damage? Nope! D-shaped exit holes from the Emerald ash border. Photo: USDA/em

Nothing can save an infested tree. It must be cut down and destroyed. The primary way this pest moves is inside infested firewood, so never transport firewood in affected states or take it outside of your state. Burn it where you cut it! If you see signs of the Emerald ash borer, click here to report it ASAP!

emAsian longhorned beetle gets its name from its incredibly long antennae. Photo: USDA./em

Scary, Gross Pest #3 -- Asian Longhorned Beetle (above) So many scary things come from Asia, like Godzilla, pu-pu platter, and North Korean haircuts. Well, here's another one, the Asian longhorned beetle. Like the Emerald ash borer, its larvae bore into trees and kill them, which must then be cut and destroyed. This beetle doesn't just stick to ash trees -- it also kills maples, birch, willow, horse chestnut, elm, and poplar. So far, it's been found in Massachusetts, New York, and Ohio, but entomologists see no reason it couldn't spread nationwide.

emPencil-size, round  holes made by Asian longhorned beetles. Bye-bye, Mr. Tree. Photo: USDA/em

Asian longhorned beetle spreads when people transport infested firewood, wood debris, logs, and branches from one spot to another. So don't do that! If you see the beetle or holes in wood that look like those above, click here to file a report ASAP.

emWhen it stings you, you'll immediately understand how the fire ant got its name. Photo: USDA/em

Scary, Gross Pest #4 -- Imported Fire Ant (above) OK, Northerners and Midwesterners! We're tired of you sending horrible, fiendish bugs down South. It's pay-back time! And what better bug to do it with than the fire ant.

About 1/4-inch long and black or reddish-brown, fire ants entered the South in Mobile, Alabama about a century ago. They've been marching north and west ever since and now have established frontlines in Virginia, Tennessee, Arkansas, Oklahoma, Texas, New Mexico, and recently, California. If you think winters are too cold for them to survive where you live, consider a little phenomenon called "Global Warming." Just wait. Your turn will come.

emEach one of these mounds contains thousands of evil, stinging ants. Photo: USDA/em

See? I told you! Those are fire ant mounds in YOUR yard! Soon there will be dozens. Accidentally step on one and thousands of angry fire ants will come boiling out. Each one can sting repeatedly. Each sting forms an itchy, painful pustule. Some poor souls even die from anaphylactic shock. And it isn't only people who suffer. Voracious fire ants wipe out all sorts of ground-dwelling wildlife, including nesting birds, and are a bane to cattle, horses, sheep, chickens, and other farm animals. They also feed on food crops, such as corn, okra, and citrus. Grumpy hates critters that steal his okra.

For you lucky enough not to have fire ants yet, the best way to keep them out is by not transporting soil, hay, and potted plants into your state from infested states. If you have them already, I wish I could give you an effective, natural, non-chemical control, BUT THERE SIMPLY ISN'T ONE. (Even Organic Gardening admits this, despite their ridiculous suggestion that you dig up a mound, dump it in a bucket, and drown the angry ants. Yeah, right -- you first.) So unless you prefer black-topping your yard or chaining your kids inside the basement, your best option is to use a lawn spreader to apply a granular, season-long fire ant killer according to label directions. You can get this at garden and home centers. It'll work for about 6 months.

Not Frozen With Fear Yet? Read more about these pests and 11 more that have you in the crosshairs by visiting the USDA website, "Hungry Pests." That should keep you awake at night.