I'm sure I've put up a few posts before about the use of dead maggots and have to say that I've used em for many years like this,
I normally buy around a gallon of red maggots at a time, take home, sieve out any debris, saw dust or maise meal and then freeze by the pint,
I seal em in a freezer bag with as much air sqeezed out of the bag as poss and then placed in large Tupperware boxes and then froze,
Incidentally it can take up to a good 36 - 48 hrs for the maggots to completely die, if taken back out anytime before this the maggots can come back to life because they haven't actually died yet, all that has happened is that there metolobism has slowed right down.
I leave mine for well over 48 hrs at the earliest before I wanna use em as dead maggots,
Once defrosted normally the night before I'm due to go fishing I then normally add some fresh maise meal to em and now because there dry from the maise they are a perfect bait to fish with,
I use a lot of em if I'm fishing the rivers when trotting for chub, dace and roach etc.
The baits that I don't really use much of these days are boilies, pellets and luncheon meat