Josh s Frogs is a leading source of quality excelsior also known as wood wool. Excelsior is ideal for use in fruit fly cultures as additional surface area for fruit flies allowing them additional places to climb mate and lay eggs. Using Excelsior in place of coffee filters provides several benefits including higher fruit fly yields and a more stable culture. Excelsior is also made from renewable resources and is compostable making Josh s Frogs Excelsior an environmentally friendly green product. This bag of Excelsior makes 10 or more fruit fly cultures.