Eulaema bombiformis, E. meriana, and E. seabrai form part of a Miillerian mimetic complex in the Amazon basin, and all three are exceedingly similar in that region. In eastern coastal Brazil all three species are found, but they are not mimetic there, and are easily distinguished. In coastal Venezuela and northern Central America, E. meriana and E. seabrai form part of a different mimetic complex, and are easily distinguished from B. bombiformis, but show the same color pattern as E. meriana in coastal Brazil (the "flavescens" pattern). It is thought that these mimetic complexes evolved in isolation in Pleistocene refugia, and that the "bombiformis" pattern of Amazonia has invaded trans-Andean Colombia and southern Central America, where it is replacing the "flavescens" pattern in E. meriana and E. seabrai. Critical features are illustrated, and a key to the species Bulaema is presented, together with taxonomic and biological notes. MIMICRY IS EASILY RECOGNIZED when it involves distantly related organisms. When very closely allied species are involved in a mimetic complex, however, even the keenest observer may fail to distinguish them. Large bees of the genus Eulaema are frequent in all wet or moderately wet lowland forests of mainland tropical America, and in many areas these bees show the classical aposematic colors, red, yellow, and black. The females, which are often seen along trails gathering mud for nest construction, have large ovipositors, and their sting is very painful. These bees are feared and respected by the natives wherever they occur. There are, as one might expect, Batesian mimics, such as two asilid flies, which, in flight at least, mimic Eulaema quite accurately. Further, there is a Miillerian mimetic complex within Eulaema and the related genus Euplusia. The mimetic species of Euplusia have been recognized as distinct species for many years, as has Eulaema (Apeulaema) boliviensis. Moure described Eulaema (Eulaema) seabrai in 1960, and found several morphological details which will distinguish E. seabrai from the related E. meriana. In 1967, Moure described additional members of the E. seabrai complex from other areas, and noted that in some areas there seemed to be distinct color forms in the meriana complex, while in other areas it seemed quite impossible to distinguish these same forms. Further work has shown that there are two distinct species through most of tropical America. In a few peripheral areas, where these two species do not mimic each other, they are easily recognized, but throughout the Amazon basin they are exceedingly similar, and almost impossible to distinguish in the field. Working with orchid pollination in Central America gave us the impression that there were two, slightly different, large eulaemas involved, a "big meriana,"