I've fed them fruit flies before, but I've never really given them the attention that would allow them to last longer than a few weeks. I kept them in pill bottles and moistened the paper towel every couple days.
They do have an entertaining snap-neck attack. They don't seem to be very effective with it on fruit flies, but they seem to get lucky at some point because when I return later the flies are eaten. I've got a photo somewhere of an individual I caught that was trailing a long white string with a white ball. Looked very much like a spermatophore, but I never asked anybody that might know. I'll see if I can (quickly) find that photo...