Africanized honey bee swarms in Costa Rica displayed no size preference among pulp-based nest cavities molded to internal volumes of 13.5, 24 and 31 I. In a crossover experiment where only one cavity volume was available at a site, European honey bee swarms selected 68 cavities of 31 I volume and only 22 cavities of 13.5 I volume. When given a choice of either 31 or 13.5 I cavities, European swarms occupied the larger cavities in 84% of the choices. No correlations between swarm size, swarm date, and size of cavity inhabited by a swarm were observed among 82 European swarms measured in Tucson, Arizona during the 1993 spring swarming season. The results indicate that 13.5 I cavities are best for trapping Africanized bee swarms since they are rejected by most European swarms.