The flies, originally from East Asia, were discovered in Latah County in 2012, then again this June in an orchard near Fruitland on the Idaho-Oregon border.
On Friday, Jim Barbour, UI Parma Research and Extension Center superintendent, said drosophila numbers appear low.
That may be because Idaho's climate is too dry and hot.
Spotted wing drosophila have robust egg-laying organs, allowing them to puncture ripening fruit's tougher skin rather than simply depositing their offspring in overripe or damaged fruit.
Despite apparent low numbers, scientists suspect the flies are here to stay, so they'll need to be watched.