: an act of showing someone how something is used or done : demonstration. 1  I saw a demo on how to use the computer program. 2  The salesman gave us a demo of the vacuum cleaner, and it seemed to work very well. [+] more examples [-] hide examples [+] Example sentences [-] Hide examples 3
If however, you are talking about some maggots in a bowl of wet food (either canned food or dry food which got wet or which you deliberately added fluid to) it is a different matter. Maggots come from flies eggs and they take some set period of time to hatch from the eggs.
If you are farming maggots for personal fishing bait, or to destroy organic waste, then the species of the maggot or fly will not be important so you can harvest your own flies to start your maggot farm. Harvest adult flies from your backyard. Prepare your large plastic containers or maggot cages.