Leon,
On your question on how to recognize when a particular fig needs wasp...?
Through centuries of fig farming we became aware of what cultivars needed pollination from the Caprifig and this because in the absence of the insect for whatever reason, a number of varieties would not set fruit.. these were the Smyrna types and in the same group there was also the main crops of different trees, rather popular for their big brebas..(the San Pedro) like Lampeira Preta, Desert King, Dauphine and others.
What those same farmers also got to know, again through many seasons cultivating figs, was that all other figs (Common) would greatly benefit from pollination. The insect once out of the Caprifig loaded with pollen will try and caprificate ALL figs.
It was soon recognized that when pollinated, Common figs ripen much better fruit, tastier, and bigger in size/weight.
Remember that those farmers did not grow figs for fun.. it was business ! On a good year with plenty of pollinating wasps it was usual to have an average increase of at least 15 to 20% on weight .
If you have a completely unknown fig it is not possible to tell if it needs wasps or not. You have to test it. If the majority or all figs do not set, there is a strong chance that you have a Smyrna variety.
Sometimes a few Smyrna figs show apparent signs of being ripen without any wasps.
This is false ripening- the syconium had just changed the skin and flesh structures/colors and the full inflorescense was not pollinated..thus no seeds, no taste no sugars etc..
Hope this helps
Francisco