There are legions of them. Mormon crickets crawl. They leap. They destroy everything in their path. Nothing can halt the attack of these armored masses.

No, this isn't a B-grade sci-fi flick. It's not a biblical plague, although early Mormon settlers in Utah thought as much when hordes of Anabrus simplex Haldeman -- the scientific name for this two-inch, shield-backed, short-winged katydid -- descended on them in 1848, devouring their crops.

Desperate for salvation from the pestilence they believed God sent them, the settlers prayed to rid themselves of what they called "Mormon crickets." According to church legend, their prayers were answered when a flock of seagulls swooped down to feast on the insects.

If burgeoning populations of Mormon crickets in recent years are any indicator, ravenous bands could be poised to march across the western United States and Canada. Idaho, Utah, Colorado and Wyoming are typically hardest hit, spending millions of dollars to control the cricket migrations and the damage they do.

During a 1937 outbreak, crop damage amounted to $500,000 in Montana and $383,000 in Wyoming. In 2004, Congress made a special appropriation of $20 million for Mormon cricket control.

Three researchers are studying the crickets' migration by attaching tiny radio transmitters to them that chart their migration path. The goal is determining if better ways exist to stop the migration from hitting certain states, either through killing the crickets or diverting their migration path with concentrated and targeted pesticide application.

Containing the Swarm

"Little is known about what causes increases in population size," said Patrick Lorch of the University of North Carolina's biology department. "We know extended drought, early spring snow thaw and overgrazing all seem to favor high cricket densities. They lay eggs in the soil, and the eggs can sit for several years, hatching when conditions are most favorable."

Mormon crickets' culinary tastes lean toward succulent forbs, or broad-leaved flowering plants, but they'll graze on desert grasses before moving to greener pastures.

Insatiable, the insects engulf rangelands, laying waste to cultivated crops such as wheat, barley, alfalfa and clover. Experts say swarms of the crickets can cover a mile a day and eat everything in their path. Some packs stretch several miles wide and 10 miles long.

"A farmer might not see a single cricket one day but end up facing millions the next day because they move in such large groups," explained Gregory Sword, a USDA Northern Plains Agricultural Research Laboratory research ecologist in Sidney, Mont. "They can potentially eat everything in the field."

As unpredictable and destructive as a tornado, the ominous black band of crickets inexplicably shifts direction, decimating one field and sparing the next. In a moveable feast, the band can overrun communities, consuming ornamentals and stripping vegetable gardens bare. There have even been accounts of them chewing wood siding off homes.

In addition to the crop damage they do, the crickets also pose a threat to public safety.

"When their bands cross roads, they tend to mass together and cannibalize the crushed dead bodies of other insects," Sword elaborated. "These in turn get crushed by more passing vehicles, leading to large, messy 'oil slicks' of crushed crickets."

Until recently, when cricket bands were on the run, no one could predict where or how far they would travel. A study of Mormon crickets conducted by Lorch, Sword and Darryl Gwynne, a zoology professor at the University of Toronto, sheds new light on accurately tracking the Mormon cricket's migration habits. Together, these scientists devised a way to bug the pests that have been bugging humans for more than 2,000 years.

Tagging Crickets

Radio transmitters about the size of a dime and weighing 0.5 grams were hot-glued onto the backs of adult female crickets.

Sue Owens Wright  |  Contributing Writer