I watched some videos about how frequent people feed veggies to their mealworms. And some say occasionally, my guess would be like a piece of carrot for two weeks or even longer? Some say replace the old ones when you realize it's all dried out. And some say always provide them fresh veggies or replace the old ones as long as you have fresh ones. So I wonder what frequencies are the best to raise them. Thanks.
If you use high quality food, they don't ever need vegetables. I give them to mine a couple times a week when they are available. They are a good source of water, and they seem to like them. If you leave them in more than a day, they may start to get moldy, so I don't leave them in there. Whatever they don't eat in a day goes in the compost bin. I also don't put too much vegetable matter in at a time because too much moisture will make their regular food get moldy and you definitely don't want that. I wouldn't over think it, there is lots of room for error with meal worms.