Are there any organisms with larva more advanced than adult form?
First let me agree with the commenters that your question doesn't really make sense.  Nonetheless here's an example that you may find interesting. Arachnocampa are insects that spend almost their entire lives as larva. These larva spin silk trap lines which capture and poison prey. They can only live in windless places (wind will mix up the lines) so to lure insects into caves they glow. By contrast their imago forms are short-lived poor fliers which are unable to eat.