I order between 50k and 100k mealworms at a time.. what I do is set them up in plastic bins with oat bran for bedding and place them into our reptile fridge. About once a week I bring them out to room temps and hydrate them with sweet potato for 24 to 48 hours and then remove the food and place them back into the fridge.
About a week before I want to feed them to my geckos I bring them out of the fridge and gutload them with apples, sweet potato, veggies and then I place them into a calcium dish inside my geckos cage to be consumed.
I also buy some a few sizes smaller then what I need since no matter what you do they will grow. That way you will have a pretty constant supply as you feed off the size you need and the smaller ones are growing until you need them. Helps when you buy in bulk![]()