Thousands of them light up a magical spectacle at dusk in the old-growth forests on reserves like the Piedra Canteada park, about 45 miles (75 kilometers) east of Mexico's sprawling capital city. Piedra Canteada in Tlaxcala state isn't a government-run park, but a rural cooperative that has managed to emerge from poverty and dependence on logging with the help of the fireflies. For years, economic forces, including low prices for farm produce, forced rural communities like Piedra Canteada to cut down trees and sell the logs. [...] in 1990, community leader Genaro Rueda Lopez got the idea that the forest could bring tourism revenue from campers. Five years later, the park's cabins and camp spaces are sold out weeks in advance, with the attraction especially popular among families with young children and couples seeking a romantic setting.