My local petsmart sells a flightless fruit fly culture in a clear tube. Could I put the tube in my substrate so just the top sticks out...will that work to continue to culture them while keeping them in the tank? Only my small gray tree frog seems to be a fan of the fruit flies, but I think it is a good extra snack for him because he doesn't eat much when it comes to crickets. Right now there are some fungus flies in that tank from one of the plants, but I'm thinking about when I move him to the new viv and lose that free food source!