Fruit fly is a significant pest and I'm getting feedback it is attacking tomatoes, stone fruit and even fruit not usually touched such as mangoes and apples.
This is a result undoubtedly of the removal of the only truly effective control for this pest, Lebaycid, without a suitable replacement.
It's vitally important you work proactively to beat fruit fly if you want to harvest a crop and stop the pest from damaging the crops of others, including orchardists who have a massive challenge on their hands.
Yellow sticky traps will work to some extent. Baits in trees will also help.
My friends at Jetto's Patch in Maida Vale use fruit fly exclusion bags, individually wrapping fruit as well as exclusion netting draping whole trees.
Yates' fruit fly spray has the same active ingredient as Success (spinosad), which are both good for controlling grubs, which may not save your fruit but will stop the spread of the fly.
The most important thing now is to pick up fallen fruit, pop it in a black plastic bag, seal and lay it in the sun for three to four days before disposing of it in the bin.