Just the standard size mesh screen that keeps out mosquitoes and flies. This thread is very long, but somewhere there are photos posted showing the cut out trays with screen glued over them. If not mine, others have also posted their setups. Just start at the beginning and click through until you see what you're looking for. If you don't find any that answers your questions, let me know and I'll photograph my trays and post them.
I bought 500 mealies last week and found this site! After reading so much on here I went ahead and ordered 5000 more lol Just a little excited to start my farm! One of my teen DD's has been raising snakes, a leopard Gecko and a bearded dragon so it just made sence for me to raise mealworms for my birds and she is raising crickets, mealworms for her critters. I am a beekeeper with a large apiary and just love bugs! LOL I am useing a 7 bin tower. My DD is doing a 1 bin set up so we will compare our reults to see works better lol I am useing oats, chick feed and cornmeal. That is what I had on hand but after reading this thread, I am switching to wheat bran, oats and chickstarter baked in the oven, I dont own a microwave. I only have one bin drawer wih worms so I can switch out and start with mite free substrate I hope! I am feeding carrots, apples and spuds. Right now my 500 are in a bin drawer on my incubater staying warm.(after reading about it on here! Thanks for the advice!) I found 3 pupa today! I shhuld get the other 5000 on Friday or Monday!! Thanks everyone fkr providing such a wealyh of adivice and information here, it has helped me so much! I am off to finish reading the rest of this thread now 