I find per Rick Shory the idea of particular interest to me even though I have pears which I have never seen apple maggots infested in. So thanks for sharing that. I have heard the name around our events before. The part that I liked is seeing the connection he made of fruit flies being attracted to the same high nitrogen food sources as apple maggots do. 

I associate another fly (eg. SWD) as flies in the same class as fruit flies as far as looking into more ways of trap designs. This other model which as tested and used (SWD) can be viewed. Try getting to where the trap is listed by placing - site:scholarworks.uark.edu three+component+Trẻcẻ+SWD exactly as shown into a google dot com search. When a large multiple page PDF loads then use the browser search tool and enter - figure 2 - and enter twice will land on an image with red plastic.

It might kind of depend on which kinds of ingredients are easily enough available. for example Rick seems to elude to the fact spinosad as being one of the important and not so easily found of all the ingredients. Then substitute annona extracts from seeds for spinosad might work too because I had found an old article of a study of which annona species types from Brazil that had been effective in killing fruit fry larvae. Pawpaw seeds have the same thing of which some of us such as myself have.

Oh. I think I found part of the last reference, though not directed at flies specifically. So the one is here.