F/A-18 Super Hornets Launch 103 Perdix Drone Swarm in Successful Test

What happens to the swarm afterwards? Do they stay in the air forever? Self-land in a neat, organized fashion? Or do people have to go track them down?

Also, what is the purpose of this class of drone?

EDIT:

Searching "perdix drone" surfaced more information.

    Perdix drones are the
    main subject of an
    experimental project
    conducted by the Strategic
    Capabilities Office of the
    United States Department of
    Defense which aims to
    develop autonomous
    micro-drones to be used for
    unmanned aerial surveillance.