Really, I just made a gallon of the stuff, and it's sat in an old orange juice jug for several months. I dont' worry abotu it getting laden with bacteria, since it's devoid of nutrients. I use the same stuff as a backup for veggies. I do not like introducing water to crickets - too messy. I keep them as dry as possible, and I have few die-offs.
I'm not concerned about bacterial growth in this stuff, and I'm a health inspector!
Here's something to worry about - cooked foods. This is why I don't cook my silkworm chow - Cook food, and you eliminate the common bacteria, salmonella, e-coli, etc. BUT the spores from the other bacteria remain. These bacteria, like clostridium species, are out competed by the other bacteria, so they don't pose a health problem in raw products. But kill off the others, and they have a free run of the place. They form spores, so it's almost impossible to kill them with simple heat.
That's why you NEVER let cooked food get cool and sit out.
Most spoiling bacteria are no big deal, healthwise. But these things will kill you. They make a poison that will make you sick within hours. So even if the food is RE-COOKED, the poison is still there, and you get sick. (botulism is one of them)
I have often wondered if this is why so many peopl ehave dieoffs with silkworms. I usually do not, and I never cook their food - just mix with warm water, throw it in a bag, and put it in the fridge.