Wasps, like most insects have clear roles for each member of the colony. Basically, everybody makes sure the queen is doing ok making babies. Everything works like clockwork until a Svengali-like fly larva takes over a wasp and makes it do its bidding.
Wired reports that after taking control of the European papers wasps by burrowing into their abdomen, the X. Vesparum fly larva feeds on the wasps, makes them fly to a secret parasite rendezvous so the parasites can reproduce — where the wasps with the male parasites die after the parasite emerges from the wasps belly — then makes the wasp think it's a queen.
The former worker wasps grow fat and happy along side the actual queen wasps. But instead of reproducing, the infected wasps wait until the actual queen is out foraging for food and starts dropping larva around the colony. The larva infect worker wasps and the weird cycle starts all over again. [Wired]