Termites are often observed following lines drawn with certain pens, a behavior frequently seen in classroom demonstrations. This phenomenon reveals insights into these insects’ sensory world, as specific types of ink inadvertently guide them along the drawn path. This common observation prompts questions about the underlying reasons for such an interaction.
The Unexpected Attractant in Ink
The attraction termites show to ink lines is not universal across all pens or colors. Research indicates that certain ballpoint pens, particularly those with blue ink from brands like Bic and Papermate, are most effective. The key lies in a specific chemical compound found in these inks, identified as 2-phenoxyethanol. This glycol ether serves as a solvent that helps the ink flow smoothly and dry quickly.
However, 2-phenoxyethanol is not present in all ink types, explaining why termites do not react to black or red inks, or those from felt-tip or rollerball pens. Its presence in the ink, rather than any other property, is responsible for eliciting a termite response.
Termite Trail Pheromones and Behavior
Termites, particularly the worker castes, navigate and communicate primarily through chemical signals. Since many worker and soldier termites are blind, they depend on these chemical cues, known as pheromones, to organize their activities. These pheromones are released from special glands, such as the sternal gland, as termites move, leaving an invisible chemical trail.
Trail pheromones guide other colony members to food sources and help them return to the nest. Termites detect these chemical signals using specialized chemoreceptors located on their antennae. The composition of these natural trail pheromones can vary among species, often consisting of alcohols, aldehydes, or other organic compounds. This reliance on chemical communication is fundamental to the colony’s survival, enabling coordinated foraging and social organization.
The Accidental Mimicry: Why Ink Works
Termites follow ink lines due to accidental chemical mimicry. The 2-phenoxyethanol in certain ballpoint pen inks structurally resembles natural termite trail pheromones. This chemical similarity causes termites to perceive the drawn ink line as a legitimate trail laid by a fellow termite. Their sensitive chemical receptors detect the ink chemical as if it were their own species-specific pheromone.
When a termite encounters this ink, its instincts prompt it to follow what it interprets as a path to a food source or back to the colony. This highlights the specificity and sensitivity of termite chemical detection systems, which are finely tuned to their natural pheromones. The attraction is not due to any nutritional value or inherent property of the ink, but because 2-phenoxyethanol’s chemical structure mimics a compound essential for their communication and survival.