Mountains of northwestern South America to Costa Rica.
From Wild 2007:
Linepithema piliferum is a montane species, with records running from 780 to 2340 meters. Where explicit habitat information has been recorded, three collections are from sifted litter in wet forest, five from cloud forest edge or roadside, one from 2nd growth forest edge, and one from a Psidium guayaba orchard. Four nest records are from under stones and one from soil. Two port-of-entry intercepts into the United States were nesting in Cattleya orchids. This species has been recorded tending root aphids, aleyrodids, and pseudococcids.
Colonies can be populous and are probably both polydomous and polygynous. I conducted three nest excavations in Ecuador in December 2002. Alate males and queens were present in all nests. Each of these nests were under series of several stones along roadsides in cloud forest. Nests contained dozens of separate brood chambers connected by tunnels, and at least one nest contained a colony of root aphids feeding on grass roots growing through the nest. In two of the colonies I found several dealate queens, each in a separate brood chamber.
In Costa Rica this species is known from mid-elevation wet forest sites on the Atlantic slope (1100m on the Barva Transect in Braulio Carrillo National Park, and 800m in the Pe–as Blancas Valley east of Monteverde. Workers have been collected in Winkler samples. It appears to be a very low density species. Project ALAS took 150 miniWinkler samples at the 1100m site, and L. piliferum occurred in only one of them. None have been collected at any other sites on the Barva Transect, where similar or greater sampling effort was carried out. In the Pe–as Blancas Valley, L. piliferum occured in two of about two dozen Winkler samples, and a worker was found beneath a stone in a trail.
Wild, A. L. 2007. Taxonomic Revision of the Ant Genus Linepithema (Hymenoptera: Formicidae). University of California Press, Berkeley, CA, USA.
Found most commonly in these habitats: 5 times found in wet forest, 4 times found in Port of entry, 2 times found in roadside through disturbed cloud forest, pasture, 2 times found in roadside through cloud forest, 1 times found in road through pasture and Psidium guayaba orchards, 1 times found in disturbed montane rainforest, 1 times found in mature wet forest, 1 times found in montane wet forest, 1 times found in road between San Miguel de las Pampas and Alluriquin. Second growth forest edge
Collected most commonly using these methods or in the following microhabitats: 2 times Winkler, 1 times Mini Winkler, 1 times miniWinkler, 1 times Search
Elevations: collected from 4 - 2340 meters, 1375 meters average