The word greenflies is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 17
Highest Scoring Words With Friends™ Play In The Letters greenflies
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Seven Letter Word Alert: (25 words)
elegies, elegise, feelers, feeling, feesing, feigner, felines, fingers, fleeing, flenser, freeing, fringes, girnels, greisen, leering, lingers, reefing, reeling, refiles, refines, reflies, reliefs, relines, reneges, slinger