The first house we owned had white cabinets and white Corian counters. It was easy to spot the fruit flies! I would just put a little piece of fruit on the counter, stand back and wait for a few minutes for them to come to the buffet ... then I would spray them with any kitchen cleaner and take them down! I usually had to repeat 2 or 3 times to get them all. They usually hitched a ride into the house with bananas.