Feeding just egg food to various foreign finches and waxbills is a complete waist of time, especially if you wanna do well breeding,
These birds are quite highly insectivorous when it comes to rearing and maggots are perfect, egg food by all means should also be given but should never expect certain species especially waxbills just to try and rear on egg, I know egg is high in protein and for some birds acts as a substitute but birds that normally rear with live food really should this available at all times when rearing
Never heard of all these funny named maggots, bush maggots and black solider fly maggots.....what ever there supposed to be

....lols
Basically there are three types of maggots, I use em in vast quantities and are an awful lot cheaper than mini mealworms,
These are the maggots :
Blue bottle ( normal size maggot )
Green bottle, called pinkies ( small size maggot )
House fly, called squats ( very small size maggot )
The pinkie and squats are what we use here in the uk and most of Europe.
I'm an experienced match angler and use a lot of of maggot and obviously know how to properly clean and use em,
Incidentally I often clean and freeze the maggots and put 1/4 pint into small freezer bags, I normally buy in excess of about 2 gallons at a time which is about 16 pints and at least 1 gallon will be frozen.
To freeze the maggots, never freeze with added maise meal or saw dust as the maggots will turn to a mush when defrosted and will then be useless,
I always add any powdered maise meal after I've defrosted em as it will now dry them nicely and look more presentable
A lot of British finch breeders here use vast amounts of the pinkie maggots with total confidence and the results are normally very good