Maggots INSIDE cockroach?! [Graphic]

[MI Hobby Entomologist]

I have had my cockroach colony for a little over two years. Today when misting my terrarium I noticed something off with one of the roaches- he just flipped upside down and started to die. These tiny white larva that look almost like fruit fly larvae started coming out of the soft parts of his abdomen, and hemolymph started draining out of the holes. 
These are not horsehair whip worms, they are much shorter and rounder, but they did seem to react to the water.

I am worried for the rest of my colony. I grabbed him and the substrate and put him in a deli cup in the freezer- will dissect later and take pictures of the maggots under the microscope to send to the local entomology department at my college once everything is dead. 

Has anyone had something like this happen before? I've never put anything that wasn't sanitized in the terrarium, and the only way in is through the secured mesh lid which has window screen over the top to prevent escapees. 
 

[MI Hobby Entomologist]

After some looking around inside the terrarium, there seems to be a few adult humpback flies, which may be the culprit. Hopefully I can get this under control and some of the younger roaches survive. The male that just passed was one of five breeding adults and the only one of two males.

[Hisserdude]

Sounds like phorid flis yeah, which will occasionally attack sickly, live roaches, in addition to mainly feeding on already dead ones. Getting rid of dead roach bodies as soon as you find them, as well as removing excess frass and ensuring there's not a ton of leftover food will help reduce or eliminate phorids from your enclosure.

[Gromphadorhini]

Definitely Phoridae. I recently had an invasion of these flies. For my collection, this is an exception, because exceptional hygiene is observed. They multiplied because I was away for two weeks and could not ensure the cleaning of corpses and sewage. I fought with them for more than two months and recently completely exterminated them. This is very difficult due to the fast life cycle of flies and the breadth of their food range. Flies just fly from the street in the warm season. A good practice in preventing their occurrence is to use a fine stainless mesh (0.5 mm) on the ventilation windows of the cages. And of course, perfect hygiene inside the laboratory cultures themselves.