A couple of days ago, three of my four VFTs seemed to be somewhat recovered, with large healthy traps open. So I decided to see how they'd do with tidbits wrapped in onion membrane (dried and rehydrated).
First: that membrane is annoying to deal with. It's as flimsy and clingy as thin plastic cling film, sticky with residue from the onions when it's wet. Next time, I'm going to try soaking it in a glass of water for a while before I try to use it. The problem is that when it's pulled into the air from soaking in water, it tends to collapse together into a wrinkled mass that's difficult to spread out. That is to say, there's a surface-tension problem.
The traps that I fed with textured vegetable protein and "earthworm jerky" have remained closed, after the usual process of tickling the trigger hairs to close the trap and then gently massaging it from outside. They appear to be digesting as normal; "candling" with a flashlight looks like there's a pocket of liquid enclosed by the trap sides. The trap that I fed with a bit of tofu is reopening. I don't know if there's a problem with using tofu in this way (remember, tofu was a big hit with my VFT last year), or if I didn't use enough of it, or if I overwrapped it, or if I just didn't stimulate the trap enough. Or if the plant is more ill than it looks, and needs to put its energy into root growth, or ..? I'll try again after a couple more days, when I'm able to remove the little packet, and the plant is ready to be fed again.