You can store the mealworms in the frig for about two months before they start to go bad. The best way to do this is:
1. Upon receiving your order, remove dead mealies (they will be black/mushy, or stiff/hard.
Put them in a container filled with wheat bedding, or rolled oats (not instant). Add enough slices of fresh potato or carrots. Let set for 24 hours for them to feed.
2. Remove potato/carrots. Mix bedding to make sure that it is 'dry'. Check again for dead mealies. Place lid (with several air holes poked through on top) over container. Put in coolest part of frig (furthest away from coldest area).
3. Repeat above steps once a week.
I buy mealworm feed from exotic nutrition, and add that to the bedding for extra nutrition.
Always make sure that the 'bedding' is completely dry, otherwise there is a risk of mold, which can be fatal to your gliders.