Observations on two neotropical swarm-founding wasps, Agelaia yepocapa andA-panamaensis (Hymenoptera : Vespidae)

In north western Costa Rica, Agelaia yepocapa (Richards) nests in cavities within living hollow trees in lower montane mesic forests; A. panamaensis ( Cameron) nests in very large cavities in premontane gallery forests. Nests of both species have vertical combs with horizontal cells that face outward from the nest center: the nests have no enclosing envelope. In January 199 6, an A. yepocapa colony was in full blood production, while an A. panamaen sis colony was in the last stage of colony decline, and a nearby A. panamae nsis colony had terminated only weeks before. The appearance of a small agg regation of A. panamaensis in a montane cloud forest site, too small to sup port a colony. as large as those that had recently reached the end of a col ony cycle in a nearby premontane gallery forest, suggests that the colony c ycle of A. panamaensis in northwestern Costa Rica Iras a seasonal pattern t hat includes elevational migration and possible non-nesting quiescence at c ool high elevations. Morphometric contrasts of queen and worker A. yepocapa confirm caste dimorphism that hus been reported for other Agelaia species. The multivariate analysis presented here reveals caste differences that ca rr only have occurred as a result of a dichotomy in developmental pathways during larval growth. Individuals of both species performed the behavior of gaster flagging during colony defense. The role of gaster flagging in thes e wasps is unknown. Near-nest aggressiveness of cavity-nesting wasps is hig her than that of wasps that nest in exposed locations, perhaps as a correla te of the scarcity of suitable cavities for nesting. The sting of A. panama ensis is particularly painful. The A. panamaensis colony that was in declin e was host to diverse inquilines and a parasitoid. The A. yepocapa nest col lection included two parasitoid species.