Information on natural breeding sites of phlebotomine sand flies is scanty, due to the difficulties of isolation of immatures from the soil where they occur. The present study investigated breeding sites in several microhabitats in a "terra-firme" forest in Pitinga, Amazonas State, Brazil. Results on the efficacy of different extraction techniques used for isolating sand flies, and the temperature and the pH of the samples collected, are presented. Samples of soil and organic matter from different microhabitats, processed by floatation-sieving, direct examination, Berlese-Tullgren, and emergence cages, revealed, for the first time in Amazonas, breeding sites in five microhabitats (tree bases, unsheltered forest floor, soil from under fallen logs, soil from under roots, and palm-tree bases). Overall, 138 immatures and 29 newly emerged adults were recovered from these microhabitats. The abundance of immatures in samples close to tree bases was significantly higher than in more open sites not adjacent to tree bases. Floatation-sieving and direct examination were the most effective techniques for immature extraction and survival, respectively. Eleven species of the genus Lutzomyia s.l. were identified, with Lutzomyia monstruosa (Floch & Abonnenc) and Lutzomyia georgii Freitas & Barrett being the most abundant. Differences in the specific composition and relative abundance of the immature and adult sand flies on tree bases suggest that breeding sites may be distant from resting or aggregation sites of adults. The pH, which revealed a slightly acidic soil, as well as the temperature, did not show any significant correlation with the number of immature sand flies collected.