I make ice cubes out of blending fruits and veggies (and pollen/spirulina). Then empty the icecubes in a ziploc bag and Im good for a long time (only 3-4 colonies though). The ice cubes stay pretty solid and dont mold if eaten in a few days. I throw one or two ice cubes in once or twice a week, plus the carrots.
I know fall and winter squashes like pumpkin, spaghetti squash, acorn and butterbut squash - will keep for a really long time on your counter. Those that Ive fed whole seem to not rot or mold too quickly - they might be a good addition to your mix or rotation?
Since you are bio - you can also grow some food in the more humid setups, if it gets some light. The rye and wheat seeds I sent germinate super fast and in relatively low light. My grasshoppers have been mowing it down. The downside is gives the roaches a boost up closer to the lid