The taxonomy and ecology of wild-caught Anopheles marajoara mosquitoes derived from rice fields in Frederick Settlement, Trinidad, were studied in the laboratory using specimens identified with species-specific random amplified polymorphic DNA (RAPD) profiles and recently developed rDNA ITS2 polymerase chain reaction methods. Adults were collected using Shannon traps and human bait in 2 houses over a 1-year period. All mosquitoes collected were taken to the laboratory, where they were identified, wing-length measured, and parity rates determined using standard methods. In addition, 25 females were blood fed and subsequently offered a blood meal every 2 h for a 60-h period. Based on the morphological keys and molecular tools used, the presence of An. marajoara is confirmed in Trinidad for the first time. Analysis of the seasonal distribution of An. marajoara revealed that over 58% were collected during the rainy season. The wing length of 660 females measured averaged 2.90 ± 0.130 mm, with no significant differences being observed among the parous and nulliparous females' wing sizes (2.90 and 2.92 mm, respectively). In addition, the monthly parous rate was not significantly correlated with mean wing-length over time (r = 0.157, df = 16, P > 0.07). Results from the blood feeding studies showed 85% of females blood fed immediately (hour 0) after capture in the field. However, blood feeding declined thereafter until 24 h later, when over 40% refed. This study clearly identified the presence of An. marajoara in Trinidad and provides information of the seasonal abundance and blood-feeding behaviors. These results suggest that this species can play a significant role in the transmission of malaria within its geographical range in the Neotropics.