Army ant attacks by Eciton hamatum and E. rapax (Hymenoptera: Formicidae) on nests of the Amazonian bumble bee, Bombus transversalis (Hymenoptera: Apidae)

This report contains details of the attack by army ants of the genus Eciton on colonies of the Amazonian bumble bee, Bombus transversalis. Attacks were made on two colonies in different regions of Amazonia by two different species, E. rapax on a colony in the Tambopata River area of Peru, and E. hamatum near the Javarí River in Brazil. Observations of the Peru raid include descriptions of the time-course of the raid and subsequent defense strategy of the colony, which successfully repelled the attack, in part because of its impregnable nest canopy and defending workers. The second attack was made on a defenseless colony (guards and foragers removed), destroyed by E. hamatum. Both the structure of the nest and a defense force come into play to withstand a raid. Ant-repellant substance(s) may be employed and should be investigated.