The behavior patterns of Exaerete smaragdina (Guérin-Méneville), a cleptoparasite of Eulaema nigrita (Lepeletier de Saint Fargeau), are described. Included are nest-searching behavior, behavior in the nest of the host, interactions between the host and parasite, and egg placement and number of eggs per host nest. Evidence suggests that the cleptoparasite's sting (or perhaps metasomal apex) usually kills the host egg (or possibly first instar) and that the second instar is capable of killing the host egg and the eggs (or young larvae) of other cleptoparasites in instances of multiple parasitism. Comparisons are made with Exaerete dentata (Linnaeus), the only other member of the genus whose behavior has been studied.

The mature oocyte of Exaerete smaragdina is described and found to be small relative to the intertegular distance of the female (egg index 0.55). Also described are the five larval instars of this species; the last larval instar is compared with last instars of other Euglossini whose larvae are known.