Sorry, got delayed in posting crickets were jumpin... So we pickup about two weeks after first post. The fruit fly population dwindled and the home owners relaxed their efforts and suddenly the flies multiplied by two or three-fold. The homeowners were determined to take care of it themselves and continued using all the methods and more. They were all over the place...upstairs bathrooms, plants, sinks, kitchen table attacking anything organic. They are extremely quick moving and tiny. They tried several other methods: still used the cider method, red wine with soap drops, over-the-counter fly solutions (same thing as the vinegar or cider), they used the old fashioned fly swatter (but flies smartly landed on glass cups & places you couldn't swat. Tried window cleaner on mirrors and bathroom counters (the smell attracted them but they quickly flew whenever sprays or swatters were near). Also tried fruit cleaning spray (contains oil in it so helps slow them down). The homeowners were constantly cleaning, washing trash cans, spraying lysol and using wipes all over the place. All fruits and veggies were sealed and stored in the refridgerator. Luckily they were busy and not eating home most nights. The homeowners put up a good fight but the flies kept coming.
It reminded me of the movie Mouse Hunt...
Hairspray was my idea! Spray hair spray on them while on the mirrors and counters of the bathroom and freeze them. This worked but was a temporary solution. Within a day or two they became resilient to the spray and could move after a few seconds. So, spray and freeze them, then quickly wipe them up with a tissue and toss. It helped but there must have been another source.
By the third week all these methods helped alot but the fruit flies were still around.
The homeowners were tired of battling them and called in the professionals.