Blue

Electric fly killers have three basic functions, all of which must be present if we are to have an effective fly control system: they are to attract, to kill and to collect. Attraction is achieved using lamps that emit Ultra Violet light. As UV light is invisible to the human eye traditional UV lamps had phosphors added which produce visible blue light enabling us to see when they are switched on.

This blue colour has no attractant power and is purely an indicator.

From: Fly Killers: The Myth and Magic
By: Paul Sidebottom

The ocean blue appears so far away.
I often wish to drink the center spot,
that all the sea surrounding me obeyed
my words and bowed in homage of my clout.
The sky appears so blue. I wish to fly
upon the wind and tear between the geese
and clouds. And I would fly beyond the sky
and view the peons trembling underneath.

The blue harmonic buzzing calls to me—
Ambition calls me. Dare I break the clasp
and free this vast potential? Dare I free
the strength and hope once kept beyond my grasp?

I wish no more: my blue cylinder
is here—Touchable—Kissable—Power.