Our animal friends the snail and slugs are lovely in their own realm, but they occasionally tread into our view by leaving an iridescent trail across our window screens. The proteins in their slime trail do not lend to the trail breaking down naturally very quickly and squirting with the hose even with pressure is usually not enough to remove the trail entirely. The good news is a household scrub brush with natural or plastic bristles and water together can usually handle the job with dispatch.
Remove the screen from the window. If the screen cannot be removed from the window frame, simply make sure the window is completely closed and locked tight before working with water on the screen.
Lean the screen against a wall or lay it down on a flat surface with the slime trail facing up and towards you.
Wet down the slime trail on the screen with clean water from a hose or watering can.
Wet your brush in the water and begin on one end of the slime trail brushing in a gentle circular motion working to the other end. Rinse with water and go over the trail once more with your brush to remove any last traces of the visitor.
Rinse the entire screen thoroughly on both sides and tap gently on a firm surface to release the water from the screen grid cells. Allow to dry and then replace the screen in the window frame.