Planidium

A planidium is a specialized form of first-instar insect larva, seen in a few families of insect species that have parasitoidal ways of life. Planidial instars generally are flattened, highly sclerotized, have functional legs or other means of locomotion, and are quite mobile. Some species have eyes, others not. The function of the planidial stage is to find a host on which the later larval instars may feed, generally until the insect pupates.