Ah, no, mold is not a "good thong". If it gets a good start ahead of the maggots it will starve them. If the maggots get the lead, they will often eat the mold as well, but there is no way to predict which will get the jump on the other. Also, some molds, particularly those that grow on grain flour, release poisons (mycotoxins), which won't do yr maggots any good, either.
Most members of this forum, so far as i can tell, use a splash of vinegar (how much? No one seems to know) as a fungal retardant. This is a bit like useing silver salts or hydrogen peroxide on a grossly infected wound when there are sytemic and topical antibiotics handy (and yes, your doc did a C&S and you're not allergic).
The antifungal of joice is Paraben, available from Josh's frogs for about $11 for 1 lb. 1 tsp treats 21./2 cups of dry material, so it lasts a long time. It is used in all ff labs, so far as i know. A second antifungal, used in labs when a particular substrate has a high (alkaline) pH, is Propionic acid available as the calcium salt (calcium propionate) in the baking stuff aisle of your local supermarket (except in Yuma). The only reason to ise it in FF food is because it might be cheaper or easier to obtain. The yeast fermentation, obviously, renders the mixture mildly acidic.
@Ben: Mites as qell? They will stick to the FF pupae and contaminate the next culture. The easiest solution is to start over. Good luck, and let us know how you make out!
Also, although they don't completely eliminate the possibility of a mold infestation, clean hands and clean utensils will help.