Old World Oraseminae were revised recently and a phylogeny proposed; however, nothing was known at that time about the biology or immature stages for genera other than Orasema. The immature stages, habits, and host associations of Timioderus and Orasemorpha are herein described, and a new species of Orasema, O. monomoria, is described based on material reared from a species of Monomorium (Formicidae: Myrmicinae) in Madagascar. Using this new information, the relationships of Old World Oraseminae were reanalyzed. After successive weighting of 48 trees, a set of six trees (length 191, retention index 0.80) was found that matched the earlier hypothesis. To better evaluate behavioral traits of Oraseminae, nine species groups of Orasema from the New World were characterized and included in a separate analysis, resulting in 54 successively weighted trees (length 204 steps, retention index 0.81). Results suggest that a host shift to Pheidole (Myrmicinae) and internal parasitism of the host larva by the first-instar larva, with a later shift to external parasitism of the pupa, are derived for Oraseminae. All Oraseminae deposit eggs into punctures formed in the plant tissue by the ovipositor, but the habit of laying single eggs is plesiomorphic for Orasema and laying multiple eggs is derived for Orasemorpha and Timioderus. The use of an intermediate host for gaining access to the ant host appears to have been derived twice within Oraseminae.