秋の鹿は笛に寄る

Etymology
Literally "The autumn deer comes to the whistle". Since autumn is the mating season for deer, hunters use whistles imitating the sound made by female deer in order to catch the deer.

Proverb

 * 1) people may bring about their demise for love (like a deer coming forth when it hears a hunter's whistle in mating season), it is easy to have one's weak points taken advantage of