Living With Horizons

Ant Feeding on Immigrant Green Leaf Weevil

Insect vision is not good at imaging fine detail, but it does provide a wide angle view of the environment. Insects, including ants, can use a UV/Green receptor system to accurately detect the line between earth and sky. UV light brighter in the sky than the land as well as brighter in the direction of the sun. Green light is of roughly equal intensity in the sky and on the ground and varies only with the direction of the sun. A visual system that subtracts the green light from the UV light will process and image that is light in the sky but dark on the ground. This allows insects to accurately detect the horizon. Horizon detection helps flying insects avoid crashing into the ground and allows terrestrial insects to map prominent objects that define the skyline.