Planidium

The function of the planidial stage is to find a host on which the later larval instars may feed, generally until the insect pupates.

The term "planidium" is derived from the Greek language πλανής (planis) meaning "wanderer", the same origin of the word planet.

The first-instar larva in the beetle family Meloidae has three claws on each foot, and is therefore called a triungulin (plural triungula).

For instance, they may ride on the adult form of the host, or on an intermediate vector that might carry them to where their later instars might feed till they are ready for pupation.

Inclusion of the extra, functionally distinct form of larva into the life history is an example of hypermetamorphosis Media related to Planidium at Wikimedia Commons

Planidia and larva of a parasitoid wasp of the Perilampidae family .
Triungulin, later larval, and other instars of a Meloid beetle .
Planidia of a Meloid beetle in opportunistic phoresy on a male solitary bee ( Andrena carlini ), awaiting contact with a female, whose nest they then could invade.