Huh? I made comments and they went away.

These are mostly background creatures, as most of the insects. (Not every creature needs to menace people and kill adventurers to be noted in the world write up.) See Codex this is attached to Insects (and Spiders and other creepy crawlies) to see the rules this post was written under.

Note to everyone, please look at the scrolls/ codices attached to a post, so you know if it is following certain rules.

As for the use, uou would use them as you would use fleas and roaches to show filth and inattentive housekeeping, but for magic users.

The creatures eat magic bits... incomplete spell castings, so barely successful or just non successful castings will leave, left overs. Good casters never generate these "left overs", shoddy or underskilled casters always do. Short cuts (fast casting, lesser phrasing, no tools) will almost always generate them.

If your system does not utilize a skill roll or control roll, then any "new spell" the character knows or one that "challanges" their level, would generate said fleas.

Good magic schools and shops have clean workrooms, bad magic schools and shops are filled with them. Do you frequent places to eat that have bugs? Do you only do it, if the place is really cheap. Extend tha analogy.

Note: Also certain powerful items will "cast off" power as they glow and act spectacular, (think of it as the smoke off a fire). So their existance or use will create a trail of manna fleas.

They are fleas, so think of them with the same kind of lifecycle and activity (hence their name).

They pass through what every dimensional planes your system uses, astreal temporal whatever. So they don't always travel distance, but sometimes just appear.

I am sorry, most of this was implied by the write up. And you might not know about threads and such if your game system does not support spells rolls.

I had not thought about the wounded MU (who would be rolling less beause they are wounded) or other magical creatures who might give off "smoke" that they might feed upon. (Tracking Unicorns by looking at the hoof shaped bunches of Manna Fleas). Good catch.

Hmmm. We could various minor spirits eat the fleas, thus magic taking care of magic. This is the option I favor.

We could have conventional insects eat them, feeding the normal ecology. However, then you get energy from nothing, so not a great idea.

Another option is that they creatures are extradimensional, coming to our world when the magic leads them here. So perhaps something from where they are... that has no material form... comes and eats them.

Either option works.

, or mayb ethere.

Yep, that is one use of the Fleas.

Of course, begining magic users will generate fleas, so schools would be extempt to a degree.

Now the shops or offices of private magic users, those should be carefully scrutinized.

Now if you have witchhunters, or someone who hunts magic users, they will be inspecting anyplace to find fleas... as a sign that magic has been performed there.

You know, that gives quite a new meaning to the age-old folkish commentary on those "filthy, flea-bitten wizards". :)