Happy Flies Fruit Fly media is precision formulated for cultivation of Melanogaster & Hydei Fruit Flies. This pack contains enough media, deli cups/lids & excelsior for 20 cultures. No need to boil water, formulated to prevent foul odors throughout the entire production process, resistant to mold (some light surface mold may appear when in high humidity environments), is made from all-natural ingredients and nutritionally balanced to produce healthy and Happy Flies.