A common practice among our ancestors at the time of summer's end (Samhain, Oct. 31) was to build tremendously brilliant bonfires. These fires would blaze the night for many reasons: Warding off maladjusted energies, soften the chill in the air, prepare harvest feasts, mark the occasion with a powerful solar symbol, etc. Anyone who has lit their own campfire knows the light magnetizes all manner of insects. In turn, their natural predators will also come to the flame looking for an easy insect meal. And so, bats were a common sight at Halloween-time festivities. By association, bats are viewed to be connected with this holiday's theme of magic and a time of passing from one phase of life to another (both in the timeline of human life and seasonal cycles). You may be interested in reading my page on the symbolic meaning of bats from a totemic perspective here.