Updated: Aug 10
Perhaps the most widespread misconception when it comes to culturing springtails has to do with moldy rice. Let's set the facts straight.
Springtails are well known in the terrarium hobby because of their mold eating and terrarium cleaning abilities, which is likely how the misconception of their optimal food source started. I'm talking about the widespread belief that springtails should be fed an excess of rice or yeast so that it molds, and this mold is what they supposedly prefer to eat. This is a misinterpretation of the facts.
The fact is that springtails prefer fresh food when being cultured. It is true that they clean up mold blooms in terrariums but they'd rather eat the fresh nutritious dry rice or yeast in their culture than the multitudes of mold that take over when they are overfed. They won't even eat many of the blue or green molds that take over their food sources!
So how do springtails eat hard dry rice? Through a technique known as rasping they use their mouth parts to scrape off and consume the nutritious starch that most of the uncooked rice grain consists of. When rice is overtaken by mold they cannot easily access the more nutritous starch and if it is not a mold which is edible to them then reproduction rates will be drastically slowed.
For optimal reproduction feed only what the springtails can eat before the food goes bad, this means before the food rots or molds. Fresh rice or yeast is much more nutrious than moldy rice or yeast, and they will reproduce at a noticeably higher rate.
Is rice even a good choice of food for feeding springtails? Yes! It is highly nutritious for most species and rice flour is a staple ingredient in many commercial springtail foods. When rice is milled into a flour it can be consumed that much easier by the springtails, and will have less of an opportunity to mold in the first place since it gets eaten so fast.
What is the best springtail food? That's complicated. For most species currently in the hobby rice (especially rice flour) and yeast works great. In my experimentation brewer's yeast is the most preferred type of yeast but other foods, especially mushroom extracts/powders, is consumed far faster than other food sources when offered separately at the same time. But with the newfound interest in keeping the multitude of species this world has to offer, we are finding that many species prefer different foods like pollen (in the case of arid springtails) or protein sources such as fish flakes (in the case of the orange and red springtails currently available). The more species the hobby attempts to culture, the more food sources we will find to be preferential from one species to another. Moldy rice will hopefully become obsolete as we advance year by year. Bad advice will be ousted and more and more keepers will have success from finding the good advice before the bad.
In conclusion, you'll get by feeding moldy food to your springtails but you will not truly thrive. Try feeding fresh food consistently, once or twice a week, and see for yourself how much more springtails your cultures produce. Maybe even take it a step further and experiment with new ingredients like mushroom powders or protein rich foods like fish flakes. No matter your reason for culturing springtails, following best practices as we now know them today will be instrumental for the betterment of our hobbies.