Enlarge By Chris Hawley, USA TODAY Migrants prepare to cross from Nicaragua into Costa Rica near Los Chiles last fall. Guides often use cars for luggage. LOS CHILES, Costa Rica  The signs of illegal immigration aren't hard to find — groups of immigrants hurrying into the high grass, lookouts on street corners, cars picking up migrants. It could be a scene near the U.S.-Mexican border, but this is hundreds of miles south, where Nicaragua meets Costa Rica. Illegal immigration is not just a problem in the United States. It is here in the sweltering lowlands of Central America, too, as people from impoverished countries try to reach developing nations. About 86 million of the world's 214 million migrants are in developing countries, where citizens often complain that the newcomers drive down already low wages and burden shaky social services. In Costa Rica, the government has imposed new rules criminalizing immigrant smuggling, raising the financial requirements for legal residency and making it harder to get residency by marrying a Costa Rican. Costa Rica ranks 97th in the world in per capita income, at $10,900 a year — poorer than Mexico, Venezuela or migrant-sending nations in the Old World like Bulgaria and Turkey. Nicaragua, just to Costa Rica's north, is worse off: The average income is $2,800 a year, making it the second-poorest country in the Western Hemisphere, after Haiti. The disparity has drawn about 74,000 migrants to Costa Rica since 2002, swelling its population of foreign-born people by 26%. The country now has 350,000 migrants, out of a population of about 4.5 million, giving it the highest immigration rate of any country in Latin America. "There's just no work in Nicaragua, and here you can at least make something," said Ingmar Herrera, 17, an illegal immigrant in the northern Costa Rican town of Peñas Blancas, where he washes tractor-trailers on the Pan-American Highway. Working with three other men, he can wash a truck cab in 20 minutes, earning about $3. "In Nicaragua, you can't earn that in a whole day," he said. Other Nicaraguans work in construction, as maids and as security guards in San José, the capital. Some guard parked cars, collecting a few colo´nes for the service. About 30,000 come illegally to work in orange orchards and banana plantations during the harvest season, said Salvador Gutiérrez, an expert at the International Organization for Migration based in Geneva. For decades, the migrants were mostly tolerated, Gutiérrez said. But the economic slump has many Costa Ricans worried that migrants are taking their jobs. "Suddenly, you notice these guys on every street corner," Gutiérrez said. "People start to think they're everywhere, that the country is being overrun." In Peñas Blancas, Costa Rican authorities have built a mile-long, 8-foot-high wall to try to discourage migrants. But on one morning this fall, the flow of immigrants continued unabated. From Costa Rica, men with backpacks could be seen on the Nicaraguan side, hiking along a trail parallel to the wall. "We catch them and deport them, and a few days later, you see the same people again," said Dagoberto Briceño, a Costa Rican federal police officer. In the past, many of the Nicaraguans in Costa Rica would have gone to the U.S., said immigrant Cristian Martínez, 20. But stricter border enforcement and rising violence by Mexico's gangs have deterred many. The Aug. 24 mass killing of 72 Central American migrants at a ranch in northern Mexico struck fear into many Nicaraguans, Martínez said. A Mexican gang known as the Zetas had kidnapped the U.S.-bound migrants, then killed them after they refused to work for the gang, Mexican investigators say. "You hear about the Zetas killing all those people, and you think, 'It's not worth it,' " Martínez said. "Better to come here (to Costa Rica)." In San Humberto, about 15 miles south of the town of Los Chiles, officer William Araya questioned a woman he pulled off a bus bound for San José. "You're telling me you didn't just cross the border today?" he said. He pointed to her shoes, stained with red clay. "Why are your feet so dirty?" The woman would likely be deported without a fine, he said. In Peñas Blancas, a border crosser clambered back over the wall to the Nicaraguan side. "You can't help but feel sorry for them," Briceño said as the man disappeared into weeds. "Hunger doesn't need a passport." Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more