Springtails primarily eat mold, fungi, and bacteria that grow on decaying organic matter. In a terrarium, they’ll tackle all the bits growing that you don’t want in there and should not need direct feeding once the terrarium is established. That said, organic high-surface-area food sources (like this Superfood powder) will readily produce a tasty biofilm to boost their nutritional supplies. Regular supplementation is necessary when culturing a springtail colony separately on clay or another medium and can be helpful in the early stages of a new terrarium to boost their population growth.  Check out our Springtails Food Guide for more info.