The ability to recognize nestmates is an integral component of eusocial insect societies. Cuticular hydrocarbon profiles are believed to be important in the recognition process and these profiles have been shown to differ by age for some Polistes species. The effects of age on nest and nestmate discrimination are examined for Polistes metricus Say (Hymenoptera: Vespidae) workers. Age affected nest discrimination. Older (10-day old) P. metricus workers spent significantly more time on their natal nest than than younger (3-day old) workers. However, nestmate discrimination did not occur for either younger or older P. metricus workers. The lack of nestmate discrimination exhibited by either age class of workers emphasizes the potential role of a social insects environment in the recognition process. Brood stealing, parasitism pressures, resource limitations, and other environmental factors are eliminated in a homogenous laboratory setting. Polistes wasps are considered beneficial generalist predators, and the majority of their prey consists of lepidopteran larvae. The prevalence and occurrence of parasitic natural enemies are reported for early-season collected colonies of P. metricus. The strepsipteran, Xenos peckii Kirby, the ichneumonid Pachysomoides fulvus Cresson, the pyralid Chalcoela pegasalis Walker, and the eulophid Elasmus polistis Burks were present in P. metricus colonies. Xenos infestations have previously been thought to be infrequent, but X. peckii was the most predominant parasite or parasitoid over a four-year period. Life history information concerning the host-parasite relationship between X. peckii and P. metricus are provided. Forty-nine female and 58 male X. peckii were found in 51 out of 221 dissected P. metricus adults, and 19.6% of these parasites were visible only after dissection. Some dissected queens contained female X. peckii, suggesting that infested Polistes females may be reproductively viable. Significantly fewer parasites per host occurred when only females were present, possibly due to the females need for host survival as an obligate endoparasitic adult. Overall development and prey consumption of P. metricus colonies were not affected by parasitism. These results suggest that X. peckii exists at low levels of infestations within a Polistes colony in order to minimally impact colony survival.