Hymenoepimecis argyraphaga is a parasitic wasp that makes its home in lovely Costa Rica. When in the mood to reproduce, a female wasp hunts down a hapless spider by the euphonious name of Plesiometa argyra and paralyzes it for 10 or 15 minutes with a sting. In that quiet quarter of an hour the wasp lays an egg, gently attaches it to the spider's belly and departs.
When the spider recovers it goes about its business as though nothing has happened. Perhaps it doesn't remember; perhaps it doesn't want to remember. All the while that wasp egg is incubating. A week or two later, the intermission is over, and things go rapidly downhill for Plesiometa. The wasp larva hatches, stabs a hole in the spider's stomach and begins feeding off it.
In a particularly diabolical move, the larva extracts one last resource from the spider before murdering it. The infant wasp injects some kind of psychoactive substance that convinces the poor thing to spin a very un-Plesiometa-like web. When it's done, the wasp kills the drug-addled arachnid, eats it and then uses the freshly spun web to wind itself into a cocoon.
Less than two weeks later a fully grown Hymenoepimecis argyraphaga emerges, prepared to propagate in the same horrific way [source: Gambino]. Isn't nature wonderful?