The duration average of the cycle life of P. erythrocephalus (Iatitude 3°30'N, longitude 76°22'21W; 965 altitude; 23.7°C) was 110 days and ranged between91 and 131 days. Predatory capacity depends on the number of larva. The maximum number of larva consumed by one Polistes larva per day was 1.3 and the minimum was 0.08 with a mean of 0.5 hornworm larva (11 y III instar). Males were not found in nests with less than 50 cells. In nests with more than 50 cells the number of males increase with increasing number of cells until they equal the number of female. Of the 412 nests examined, 17 % were attached by Oxysarcodexia sp [(Diptera: sarcophaqidae). This insect is in turn parasitized by several hymenoptera such as Pachyneuron sp (Pteromalidae) y Brachymeria conica (Chalcididea).