ABSTRACT
Neotropical social wasps are frequently attacked by species of large army ants and are the second most common prey for army ants, which eat primarily other non-ecitonine ants. The importance and frequency of army-ant attacks are reflected in a diverse array of alarm and defensive behaviors by the wasps. Wasps exhibit some alarm responses to an approaching army ant that are identical to the responses shown toward any ant or parasitic wasp that approaches or runs on the nest envelope. Various alarm behaviors of the wasps stimulate exit from the nest before any ants have entered it. The army ants persisted, however, and were able to pull the wasps out by their antennae. The nest envelope has long been considered a defense against parasites and predators, but it is a hindrance for rapid nest evacuation. In social wasps the queens tend to stay inside nests when colonies are disturbed.
