The economy of Nayarit depends on fruit, especially mango, Mangifera indica L., and citrus. However commercialization of fruit is affected by abundant fruit flies (Diptera: Tephritidae). To know the diversity of Anastrepha Schiner and determine its population dynamics on species in marginal areas of the municipalities of Rosamorada and San Blas, between January and December 2011, 128 McPhail traps baited with hydrolyzed protein were prepared each week. Fruit flies captured were preserved in 70% ethanol and sorted by sex and species according to an FTD index of numbers of flies trapped per day. Of 563 specimens collected, 442 (78.51%) were from Rosamorada and 121 (21.49%) at San Blas, with a male: female sex ratio of 1:1.9 and 1:1.6, respectively, at each municipality. At Rosamorada (FTD 0.143), species identified were Anastrepha ludens (Loew) (210: 47.51%), A. striata Schiner (114: 25.79%), and A. obliqua (Macquart) (113: 25.57%), captured 70.2, 81.0 and 51.3% of the time, respectively, while A. sp. (3: 0.68%) and A. serpentina (2: 0.45%) occurred only rarely (2.7 and 8.1%, respectively). At San Blas (FTD 0.0111), A. obliqua (57: 47.11%) and A. striata (57: 47.11%) were captured 70.3 and 62.9% of the time, respectively; A. ludens (6: 4.96%) was found less commonly (14.8%), and A. sp. (1: 0.82%) was found rarely (3.7%). Most fruit flies were trapped between February and August, coinciding with the fruiting period, with no apparent effect of abiotic factors such as temperature or precipitation on abundance.