A nest aggregation of the oil-collecting bee Rediviva intermixta (Cockerell, 1934) (Hymenoptera: Melittidae: Melittinae) was found associated with a mound of harvester termite, Microhodotermes viator (Latreille, 1804) occupying a clay-rich bank. We first noticed this nest aggregation by the intensive patrolling of seemingly hundreds of males searching for females close to the ground. We estimate the density of nests as 194 nests/m² or 2917 nests in the 15m² aggregation. This short communication presents observations on the daily activity and interactive behavior of males and females at the nesting holes. We provide the first account for this family of the males sleeping together in burrows, rather than on flowers.