Wasco County Oregon State University Extension says according to its models, the first emergence of the Western cherry fruit fly will occur on Saturday.  The model is based on work conducted in Dr. Helmut Riedel’s lab.  According to Ashley Thompson at OSU Extension, cherry fruit flies lay eggs about 6 to 7 days after emergence early in the season, but that interval drops to 5 to 6 days during 80+ degree temperatures.  The first fruit fly covers need to be on in early locations within 6 to 7 days of emergence due to the warm temperatures predicted over the next few days.  Thompson says successful fruit fly control in the past has involved applying cover spray within seven days of emergence, keeping intervals between sprays at seven days, and re-applying as soon as possible after a significant rain.  Both cover sprays and baits need to be applied on a 7-day interval.