Information about parasitoids of neotropical vespids is scarce. Parasitoids collected from 43 colonies of Polistes myersi Bequaert, 1934 and one ofPolistes erythrocephalus Latreille, 1813 are reported from an Andean region of Colombia. Colony parasitism rates in P. myersi ranged from 35 % to 57 %, being higher in colonies with more cells; however, the number of parasitized colonies did not differ when considering the mean number of adult wasps (8.2 vs. 8.1 respectively). Parasitoidism ranged from one up to four species per colony. P. myersi parasitoids were: Seminotalaeviceps (Cresson, 1879) (Trigonalidae); Signiphora polistomyiella Richards, 1935 (Signiphoridae); Elasmuspolistis Burks, 1971 (Eulophidae, Elasminae); and a new species of Xenos(Strepsiptera, Xenidae). The latter three are first records for Colombia. P. myersi and P. erythrocephalus are the first host reports for the trigonalid S.laeviceps. We also report an unknown Tachinid fly species of the tribe Blondeliini attacking P. myersi.