"Ships that have been taken over by parasitoids are turned into sort of organic guided missiles, which are sent back to the destination where they came from. If the ships reach their destination and are opened, the change in the atmosphere inside the ship provokes the incubators to open and cause the larvae inside to spill out and spread outside. They rarely would do this, however, as their primary desire is to be left alone, but due to the way they came into being it inevitably pulled attention towards them and their destruction. Therefore spreading to other planets or outposts would be counter intuitive to their goals, as that would increase the hostilities towards them, but at the same time spreading from place to place would ensure their survival. In the end, after it became apparent that they were sentient and capable of being non-hostile, they were all incinerated, apart from a colony on one small outpost on an asteroid, which was quarantined with guided mines that would destroy unauthorized ships attempting landing there."