I'm not sure if this is commonly done, but I just started and it is working well so far! So my hornworms were growing like a bunch of maniacs and could not be fed to my Jackson's after less than a week. I had read that keeping them at about 55 degrees F slows down there growth and that temps much lower than that will kill them so that threw all of my refrigerators out of the question because we keep them very cold. Instead of buying a mini fridge just for my pod of hornworms I tried putting a quart ziplock bag of ice in a bowl with the worm pod and covering with a towel and surprisingly it works very well! I put my thermometer in the bowl and have been getting consistent readings of temps between 50 and 55. I just have to swap the ice once on the morning and once in the evening. It has proved to be an easy fix to slow down the growth of my occasional pod of worms. Hope this can help some people!