Cicadas can see, and their visual system supports their short, hyperactive adult lives above ground. The world they perceive involves rapid movement and specialized light, which is necessary for mating and avoiding predators. This sensory system gives them an advantage as they emerge from their long subterranean existence into the bright environment of trees and open sky. Cicadas see using the unique anatomy of their five eyes, which process visual information efficiently.
The Dual Vision System of the Cicada
The cicada’s visual apparatus is composed of two distinct types of light-sensing organs, totaling five eyes. The most prominent are the two large, widely spaced compound eyes located on the sides of the head. These eyes are constructed from thousands of individual light-gathering units called ommatidia, each pointing in a slightly different direction. This structure provides the cicada with a panoramic, mosaic-like view and is effective at detecting motion across a wide field of vision.
The compound eyes are primarily responsible for general navigation and spotting movement, which helps them evade fast-flying birds. The image they form is not sharp like a human’s, but it provides excellent peripheral awareness and detects changes in light patterns. Complementing the compound eyes are three small, simple eyes known as ocelli, arranged in a triangle on the top of the head. Ocelli do not form images but are specialized for measuring light intensity and detecting changes between light and darkness. They play a role in flight stability, helping the insect orient itself by monitoring the horizon and the position of the sun.
How Cicadas Perceive Color and Light
The cicada’s visual world is defined by its ability to perceive light across a spectrum invisible to the human eye, utilizing a trichromatic color vision system. Their eyes contain photoreceptors sensitive to long-wavelength light, blue light, and ultraviolet (UV) light. This sensitivity to UV light is an adaptation because the sun’s UV rays are intense in their habitat and are reflected strongly by plant surfaces and other cicadas.
The perception of time is accelerated for a cicada due to its superior temporal resolution, measured by the critical flicker fusion frequency (CFF). Many insects have a CFF significantly higher than the human average of around 60 hertz. This high processing speed means that fast movements, such as a bird’s flapping wings or a predator lunging, are processed as a series of slow-motion frames. This allows the cicada more time to react and escape. The ability to process rapid changes in light and motion aids survival against quick-moving threats.
The Role of Sight in Cicada Behavior
The cicada’s specialized vision system is applied to the tasks of its short adult life: finding a mate and avoiding danger. Both male and female cicadas use visual cues to locate potential partners, often in conjunction with the male’s acoustic mating calls. The UV-reflective properties of their wings and bodies act as a visual signal, making them stand out against plant foliage to a potential mate who can see that portion of the light spectrum.
Sight is integral to the cicada’s navigation and feeding behaviors, particularly during flight. The ocelli detect minute shifts in light intensity and polarization, helping the cicada maintain a stable flight path and control its roll and pitch. Using celestial light as a compass assists in directed movement across landscapes to find host trees. The quick detection of movement provided by the compound eyes serves as an early-warning system for predator avoidance. Their high temporal resolution helps them spot a fast-approaching threat, giving them the reaction time needed to execute an escape maneuver.