Yes, Monarchs can lay infertile eggs. Yes, eggs can be parasitized or diseased. Sorry to hear this.
I keep my vent closed in my dinning room to keep it a little warmer.viewtopic.php?f=6&t=2358&start=0&hilit=tent#p11506
Set up for using Glad Containers to Rear
I use these Glad Containers to rear inside. They keep the milkweed fresh for two days. I also raise Zebra Swallowtails in these and the Pawpaw last for two days, too without water.
The Glad containers are easy to wash in the dish washer. I just turn off the heat drying cycle and fill the whole dish washer. Lid in the bottom due to their height. I can wash 8 at a time. 4 in top, 4 in bottom with 8 lids.