The word treehoppers 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: 19
Highest Scoring Words With Friends™ Play In The Letters treehoppers
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Seven Letter Word Alert: (26 words)
heptose, heteros, hoppers, peepers, porters, pothers, presort, prophet, prosper, reports, reposer, reshore, restore, retrees, rhetors, seether, sheerer, sheeter, shopper, shorter, steeper, steerer, stepper, stopper, strophe, toppers