I order these in bulk. These pupae will last about 2 weeks in the fridge. Take the needed amount out and set them in a container. They take between 24 and 36 hours to hatch. Once they hatch, you can place the container into the freezer for 45 to 60 seconds, which will cause the flies to go dormant. They will remain like that for about 45 seconds to a minute before they are warm enough to fly again, giving you enough time to feed a few mantids. You can place the container with the remaining flies back into the fridge where they should remain alive for another 7-10 days.
One order of house or blue bottle flies will keep several mantids fed for a couple of weeks. If you are looking to buy house fly pupae in large amounts, please email me. I will put you in touch with my source to purchase directly.