Hey FutureForces,
First, Welcome to the forums!
Second, VFT's often won't eat dead stuff without help. Greenhouse1 is right about the beetles, too. Soft-shelled insects and spiders are better.
A VFT will not keep it's trap closed & digest with the stimulation of a struggling victim. This can be manually recreated by sticking a thin toothpick or something into the closed trap and wrigling the dead body, if you're trying to feed it something dead. You'll have to do this about every 15 minutes for a couple of hours...Live bugs are much easier.
At any rate, this is movement is needed because the VFT leaves are stimulate to grow closed by repeated stimulation of the little trigger hairs on the inside of each trap. You can see them with the naked eye, if you look. Most of my traps have three on each side, but some have a few more.
Hope this helps!
If someone else has a better way of describing (or needs to correct me) this, please chime in!!