。
Speak of the wolf and you see its hide.
Literal
Wolf [possessive-の] rumor [object-を] do-[when-と] its hide [subject-が] visible.
A variant of 噂をすれば影が差す ('speak of someone and their shadow falls') — the Japanese 'speak of the devil.' This wolf version is likely a translation of a Western proverb. と marks the automatic consequence.