How are flying things in stop motion filmed?

Often in stop motion animation you see items or characters flying through the air. My first guess would be some sort of wires holding them up during filming but you can never see wires, even on freeze frame, so what technique is used to accomplish this effect?

(I would like answers from somone who knows, not just guesses from lay people)How are flying things in stop motion filmed?Simple, the wires are photoshopped out of each frame in post production.