 Why have humans been carrying beetles around the galaxy?
The ice-cap, by its existence and circular shape, proved that the planet rotated at a not unreasonable rate. A water-ice ice-cap said that there were no poisonous gases in the planet's atmosphere. Without rigid control of space-travel, any criminal anywhere could escape the consequences of any crime simply by buying a ticket to another world. The process would be to find a planet and check its climate and relationship to other planets, and its flora and fauna against descriptions in the Directory. If they left a beacon, they may have left an identification of the planet. If somebody were wrecked on an even possibly habitable planet, the especially developed seed-strains would provide food in a minimum of time.
 Beetles are just one piece of the puzzle to create an ecological system capable of supporting human life.
 Beetles are just one piece of the puzzle to create an ecological system capable of supporting human life.  Beetles are a good source of protein for new planet settlers.  Beetles, like other pests, always seem to make their way on board spaceships.  Beetles are an integral part of a spaceship's waste management system.