Termites are highly social insects, but the question of their vision depends entirely on their role, or caste, within the colony. While the vast majority of termites live in functional darkness and are blind, the temporary reproductive caste develops full sight for a brief, crucial period. This difference in visual ability reflects the distinct tasks each caste performs to ensure the colony’s survival and expansion.
Visual Capabilities by Termite Caste
The worker and soldier castes, which make up the bulk of the colony’s population, are functionally blind or possess only rudimentary visual structures. Since these termites spend their lives in subterranean tunnels or inside wood, they lack the fully formed compound eyes seen in many other insects. The eyes they do possess are often severely reduced simple eyes, known as ocelli, which are incapable of forming detailed images. These organs can generally only detect the presence or absence of light, a limited ability known as phototaxis.
This minimal light detection capability may help workers avoid accidental exposure to the air, which can cause them to quickly dehydrate. Conversely, the reproductive caste, known as alates or swarmers, possesses fully developed compound eyes. Mature alates are the only members of the colony that are adapted for life outside the dark, protected tunnels.
Sensory Compensation: Navigation Without Sight
Workers and soldiers rely on non-visual senses for all colony functions since they operate in perpetual darkness. Chemical communication is primary, with termites utilizing pheromones to organize activities. Trail-following pheromones are secreted from a gland in the abdomen, creating chemical paths that workers follow to locate food sources and navigate the extensive gallery systems.
Another chemical signal is the alarm pheromone, which is rapidly released by soldiers or workers to warn nestmates of a threat, such as an ant invasion. Communication and spatial awareness are also mediated through mechanical vibrations. Termites perceive these substrate-borne vibrations using specialized organs located in their legs called subgenual organs.
This vibrational sense allows termites to detect the footsteps of predators like ants through wood or soil. Soldiers actively generate alarm signals by repeatedly banging their heads against the tunnel walls, sending a wave of vibration through the nest that alerts the colony to danger. Furthermore, their antennae are equipped with receptors that help them sense humidity and detect odor particles associated with decaying wood and fungi, which are signs of a suitable food source.
The Function of Vision in Swarmers
The functional vision of the alates is temporary but necessary for colony dispersal and foundation. These winged reproductives emerge from the colony during swarming events, which often occur on warm, humid evenings. Their fully developed compound eyes allow them to navigate during their brief flight above ground to find a mate and a new home.
Vision is used to orient the alates during flight, where they often use light cues, such as high contrast or polarized light, to maintain direction. After flight, their sight guides them to a suitable location to establish a new colony, which is typically a dark, damp crevice that offers protection and moisture. Once the alates pair up, shed their wings, and retreat underground to become the founding king and queen, their dependence on vision ceases, and they return to a life of functional darkness.