The Fly as a Life Index

The fly here represents the spirit, an idea very common in folk-lore, where an insect often appears as the Life Index. An English lady has been known in India to stop playing lawn-tennis because a butterfly settled in the court. In Cornwall wandering spirits take the form of moths, ants, and weasels. We have the same idea in Titus Andronicus, when Marcus, having been rebuked for killing a fly, gives as his reason,—

“It was a black, ill-favoured fly,
Like to the empress Moor; therefore I kill’d him.”

A fly is the guardian spirit of St. Michael’s well in Banff.