Perflare is both intransitive (blow all around) and transitive (blow through [something]). Here it's transitive. We should get duolingo explaining clues though...
Why not "Venti per silvas perflant"? I read here "winds blow the forests".
The through is contained in the "per" of "perflant"
A previous sentence was “Ventus iratus per villam perflat”.
I TOLD the hikers to stop eating beans!