-- This federal employee works along a treacherous stretch of high Rio Grande riverbank known as No Man's Land. His work uniform: leather chaps, sturdy Wranglers, high-top bullhide boots and silver spurs. His tools: a .357-caliber revolver, a lariat, a machete, a walkie-talkie, and his beloved brown-and-white appaloosa, Payaso.

His mission: to hunt down ticks.

Meet Fred Garza, government cowboy -- one of a small force of hardy men whose mission for almost 70 years has been to keep the dreaded Texas cattle fever tick confined to 900 miles of winding riverfront along the Mexican border. He is a tick, or river, rider, a U.S. Department of Agriculture employee who has managed to marry his cowboying skills and love of desolate open range with benefits and a federal pension.

It's hard and lonely work in unforgiving terrain. The cowboys live away from their families in remote shacks four to five nights a week. They ride solo six or seven hours daily in 100-plus-degree temperatures, cutting trails through thick gnarly brush and prickly cactus to rope frightened steers, searching them for ticks and then transporting them to a pesticide vat for a disinfecting dip. (The cattle are dipped regularly in organophosphates for six to nine months before being returned to their owners or sold at auction if not claimed.)

It may be a tough life, but Garza, a GS-8 after 15 years in the saddle, loves it.

"This is not work for me. It's not work for a lot of us," said Garza, a mustachioed 50-year-old whose uncle rode the river for 56 years before retiring from the USDA. "Like they say, ma'am, if you don't want to work, find you a good job."

Garza and his horseback-riding colleagues make up the nation's front line against a scourge that decimated the cattle industry in 1906 and continues to be a threat as long as the cattle fever tick thrives south of the border and Mexican cows stray or are smuggled across the Rio Grande. Mexican cows have developed immunity to many tick diseases or suffer only mild symptoms.

Today, the riders are fighting the worst infestation of cattle fever ticks in 30 years and are doing so in the face of budgetary shortfalls and bureaucratic turf wars.

"We're losing ground," said Edwin J. Bowers, director of field operations for the Laredo-based program, which is part of the USDA Animal and Plant Health Inspection Service.

The battle against the ticks dates back to 1906, when cattle tick fever spread through 14 southern states, wiping out up to 90 percent of herds in just days. The cause was traced to the Boophilus annulatus and Boophilus microplus, ticks carried by Texas cattle driven along trails to stockyards and auction markets up north. The parasites cause piroplasmosis, a disease known as Texas fever or red water disease. It causes red blood cells to rupture and the fever-crazed animals -- usually cows but also horses -- bleed to death by expelling blood through urine.

The epidemic sparked an intense campaign against ticks that began, initially, under the auspices of various affected states and counties. By 1938, the dreaded insect had been confined to portions of eight Mexican border counties in south Texas, and the federal government took over the eradication program. To patrol the permanent quarantine zone for "Mex-ee-co cows," as these cowboys call them, the USDA created a squad of river riders, some of them members of the old U.S. horse-riding sentry against hoof-and-mouth disease.

"They call us tick riders. We call ourselves the tick eradication mounted patrol," Bowers said.

In January, Bowers asked USDA officials for an emergency appropriation of $521,000 to hire two tick riders for his understaffed unit (he is two short of the full complement of 61), to pay keep on four temporary workers, to buy needed equipment, and to fund a special feeding program that kills fever ticks on south Texas's abundant whitetail deer. The deer are believed to be spreading the tick on cattle-grazing land, making it harder to contain the parasite. At the same time, U.S. ranchers have been stymied in keeping Mexican cattle off their property because of drought-induced low water levels along certain parts of the Rio Grande and regulations by the International Boundary and Water Commission that prohibit fencing and brush management on dried riverbeds. The funding has yet to be released, and negotiations with the IBWC are stalled.

"Until 1996, we hadn't had any ticks on my land in 50 years," said Humberto Vela, who owns a 2,000-acre cattle ranch in Zapata, Tex., outside Laredo. He said lax efforts by Mexican officials to kill off the fever tick and the ban on building fences in dried portions of Rio Grande riverbed have penalized him and other ranchers. "We have to go through this whole cycle of dipping to keep an epidemic out of the United States," Vela said.

In Spanish, the tick riders are called garrapateros for the Spanish word for tick (garrapata). Although 60 percent of these government cowboys are Spanish-speaking Mexican American, the Anglo tick riders are bilingual, too. The job requires regular encounters with Mexican ranchers and ranch hands across the river -- not to mention chance meetings with undocumented immigrants, usually dehydrated and starving, who get lost wandering through the thick brush; the coyotes who guide them across the Rio Grande; and other smugglers and border bandits, as well.

"I got caught in the cross-fire between the bandidos and the coyotes when I worked the river over in Brownsville. One got shot in the heart and right here," Garza said as he pointed to his upper right rib cage. "He died and the other guy got shot in the arm and leg and lived. It was 10 in the morning, on a Sunday."

Danger has always been part of a tick rider's job. In 1982, Congress passed a law to arm the patrol after a group of weathered cowboys, bullet-riddled saddle in hand, went to Capitol Hill to lobby lawmakers for help. They got .357 magnums and later, the choice to carry .40-caliber semiautomatics.

The weapons have not eliminated the casualties, however. One tick rider was shot and killed at his camp not far from the river (the case has not been solved). One drowned in the Rio Grande, and another was killed in a vehicle accident. One rider survived a bullet in the back, and many others have been shot at and missed. "We've been very, very lucky considering the climate we work in," Bowers said.

Among all of USDA's animal health technicians or animal inspectors -- as the tick rider's law enforcement badges proclaim them to be -- they are more prone to be injured on the job. One kick of an angry cow's hoof can snap a forearm.

Despite the hazards of the job, Bowers gets about 100 applicants per job opening, and some tick riders apply multiple times before getting hired as a GS-5 with a current starting salary of $26,197 a year.

Joe Akers, 37, a champion rodeo roper of the Tilden, Tex., rodeo applied three times before he got the job on the mounted patrol three years ago. Like Garza, he was following in a relative's footsteps. His uncle was a river rider for decades.

"If you like ridin' and you love ropin', this is the job for you," said Akers, who wears the big silver belt buckle he was awarded in a cattle-roping competition. "Especially in south Texas, it's extremely prestigious to get on with the tick force."

Fred Garza rides appaloosa Payaso along the Rio Grande in what often is a six- or seven-hour daily search for ticks.Jack Gilpin, assistant director for the USDA's tick-eradication program, pulls on the tail of a quarantined cow as a tick rider searches for Texas fever ticks.A horse, searched for Texas fever ticks, swims through a vat of organophosphates that will kill the dreaded tick.