I just recently started using fruit flies for feeders sometimes. They're nice because they don't need to be cut up, and for most of my colonies, they don't even need to be killed. It's also nice that they are entirely soft, so they probably don't contribute much to the ant's trash pile either.
I watched tons of videos on how to culture them, and the vast majority are basically just the same exact information. Maybe a few might do some minor things slightly different than others, but they're mostly all doing the same thing. You can buy the cups with the special lids and stuff already designed for it, but the cost of all that stuff can really start to add up.
I wanted to find the cheapest way to breed them and with the least amount of work. I also don't need thousands and thousands of them, even with the amount of ant colonies I have. We ant-keepers don't need nearly as many fruit flies as someone feeding them to a bunch of larger animals.
Well, this is what I came up with.
I use only a tiny bit of media in each of these, and setting them up is simple. I just use a funnel to pour 1/2 tsp of the powder media in them, and then give each one a full pipette of vinegar/water mixture. After sitting for about an hour, the powder soaks up all the water and swells to about one inch in height. After that I stick a popsicle stick in each one to give them the surface area they need. I use the same funnel to tap about 15 or so flies in each one and plug it with some cotton.
Doing it this way allows you to simply tap them into your ant colonies without the need to be transferring them from container to container which can be a real PITA because of how crazy they get trying to escape. Anyone who has dealt with fruit flies probably knows what I'm talking about.
Since test tubes are so cheap, I stopped washing them out years ago and just throw them away and buy new ones instead. At least now I have a use for all the used test tubes that would normally just go in the trash. Most are plenty clean enough to use for this, I just like using brand new crystal clear test tubes for new ant colonies so that's why I would normally just toss them out.
If anyone has any ideas or suggestions, let me know. I just recently started doing this, and so far it's been working great.