There are a number of different types of commencially-available fruitflies.  Our Chef prefers to serve Drosophila Melanogaster and Drosophila Hydei.
Fruitflies are prepared in cultures, which consist of some media (fly food), some adult flies, and some fly larva.  The cultures are typically packaged in 32 ounce deli cups.  Such cultures, if cared for properly, should produce thousands of flies over a period of a few weeks.
The deal with fruitflies is: if you decide to culture own supply, you have to continually be creating cultures.  This can be a difficult and time-consuming task.   One way to avoid this work is to purchase your cultures from a vendor every time you need them.  This can be costly, but it eliminates the hassle, mess and aggravation associated with culturing fruitflies. 
A typical fruitfly culture
Drosophila Melanogaster are small (1/16th of an inch) brown flies, and are well-suited for feeding smaller frogs.
Drosophila Hydei are larger (1/8 inch) and have freaky RED eyes....
killer frog hotel
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