they will do it on their own if nothing eats them..
i just attended the MMC 2006 yesterday in Ann Arbor, MI.
Sandy Shoup gets into the "bugs" of the tanks quite a bit! You can also add a refugium where they will live without bein eaten or disturbed.. It will all happen naturally, and there are TONS more bugs that live in ALL of our tanks too!!! I got alot of info from the conference, other speakers were:
Eric Borneman, Scott Micheal, and Steven Pro.