The confused flour beetle has been around a long time; remains of them have been found in Egyptian tombs and archaeological sites in the near east dating to before the time of Christ.
Especially for top feeding killifish, both the adult beetles and their larvae provide an ideal food.
Culture of confused flour beetles is simple. To a well covered container such as a gallon size plastic ice cream tub with holes punched in the lid for ventilation, add an inch or so of flour, powdered milk, or a combination of the two, and a starter of adult beetles. Put on the cover, set in an out of the way place, and ignore for a while. The cultures require little care beyond occasional freshening of the culture medium.
Although they are easy to culture, and are an ideal size for killifish food, the beetles do have a downside.
Adult beetles crawl actively; a few always seem to get loose when being harvested. Given the chance, they will infest foodstuffs. And the larvae can be difficult to separate from the food medium and their own empty pupal cases. Using a fine mesh kitchen strainer effectively separates the insects from most of the flour, but not from the shed skins; some of each always end up in your tanks, necessitating more frequent water changes.
However, some aquarists have recently found that confused flour beetles can be successfully cultured in powdered milk, either with or without the addition of a small amount of flour. To feed, simply scoop a batch of the adults and larvae from the culture medium, then rinse off using a fine mesh (brine shrimp) net. Result: clean, wet, sinkable food, with no residue to pollute your tanks. G.C.K.A. Newsletter, May 1998