One of the smaller species of rove beetle does not live harmoniously with ants; it threatens the entire existence of ants all over the world. It starts off living in an ant colony and produces a chemical that drugs the ants, making them forget their responsibilities as ants, stop rearing their own young, and it changes them into rove beetle slaves.
Once that ant colony is exhausted, the rove beetles move in mid season to another colony where they do the same thing. This time, the rove beetles only eat part of the colony and the young. The ants that are left alive after the rove beetles have feasted on the colony are still affected by the drugging and are still slaves to the rove beetles. They spend their remaining time alive looking after the rove beetles eggs and rearing their larvae.
The only way the rove beetle is prevented from completely wiping out the ants is that it has to pupate. It builds a defenceless pupa on the ground and is then completely vulnerable. Ants make the most of it and eat vast numbers of pupa, keeping the rove beetle population low enough to save their own skins.
Once that ant colony is exhausted, the rove beetles move in mid season to another colony where they do the same thing. This time, the rove beetles only eat part of the colony and the young. The ants that are left alive after the rove beetles have feasted on the colony are still affected by the drugging and are still slaves to the rove beetles. They spend their remaining time alive looking after the rove beetles eggs and rearing their larvae.
The only way the rove beetle is prevented from completely wiping out the ants is that it has to pupate. It builds a defenceless pupa on the ground and is then completely vulnerable. Ants make the most of it and eat vast numbers of pupa, keeping the rove beetle population low enough to save their own skins.