Résumé
An active first-instar larvae (planidium) is restricted to one clade within Chalcidoidea that includes Eucharitidae, Perilampidae and Eutrichosomatinae (Pteromalidae). Phylogenomic approaches have helped to identify the clade and the relationships among groups, which will ultimately lead to a revised classification of families. The morphology and behavior of the planidia and other behavioral attributes across the different groups will be reviewed, and some anomalous results discussed.