Okay, these things are cool (I borrowed these photos from the Universal Chalcidoidea Database):

That is a male Mucidifurax raptor, a wasp which parasites on Musca domestica, the house fly (I'm guessing it goes after other flies as well).
Here's a female depositing an egg within the pupa of a house fly:

I've been reading about Musca domestica because they and their larvae seem to be on the menu at Internet bug stores, such as the American Cricket Ranch, for the feeding of various critters. I just bought 150 of them because I wanted to get something for my chameleon to hunt besides crickets...they're too easy and she must get a bit bored with them. Besides, variety is important for nutrition. One hundred and fifty was the smallest amount I could get for the low-low price of just $3.99 plus shipping. Another dealer wanted to sell me 5000 pupae which would emerge in just a couple of days for $15...what would I do with 5000 flies?! I'm thinking that 150 is over the top. So I was also wondering what it'd take to raise the suckers for myself. After reading about that for a bit, I decided that it's probably something best avoided. But when I visited this page on the house fly, I was introduced to that awesome little wasp with the cool name: Muscidifurax raptor.
Check out it's life cycle:

(I borrowed that image from a page about the wasp, where it is credited still elsewhere, the Ciba-Geigy Corporation.)
The place that wanted to send me 5000 house fly pupae, Beneficial Insectary, apparently sells those little wasps to people who want rid of their flies. Remember that the next time you find yourself trying to deal with those suckers.
Posted by Jeff at April 14, 2005 10:59 PMhi my name is matt n i just baught a chamelon n i have some questions. i am waiting for my cage to arrive and i wanted to know what kind of plants i can put in there and what plants will bring out alot of their colors. also about handeling, can i? and how often? thank u for your help and your advice.
Posted by: matt at March 30, 2006 03:01 PMJust thought you might want to know that you can keep the fly pupae in the fridge and they will not hatch. Google "diapause" for the full explanation. Pull a few out at a time and you won't have 5000 flies all at once!
A little trick from me, the entomologist.
Posted by: Glen at March 3, 2007 04:43 PMcan you send for me more imformation about Musca domestica?
thank you very much!
I have like a 100 flys in my house and everyday there are more and just today i found a bunch of fly pupie i need help how to get rid of them here is my email please help randy_poo_1995@hotmail.com
Posted by: Robert at July 31, 2008 05:44 PMDear entomologists,
I am a lay person who suffers from cricket/grass-hopper (it is a brown medium-size insect which does not actually make sounds and jumps while moving) infestation on the ground floor of a private house where I rent a room. If anyone can suggest how I can get rid of these insects I would greatly appreciate it.
AS
Posted by: AS at September 4, 2008 10:09 PMeww this is nasty
Posted by: hi at September 29, 2008 11:15 AM. Original Copyright, May 2004. All Rights Reserved.