Why Do Termites Follow Ink Trails?

Ballpoint pen manufacturers don't seem keen on advertising a little known but well-documented feature of their products: the ink from these pens attracts termites! Draw a line with a ballpoint pen, and termites will blindly—literally, blindly—follow it across the page. Why? Here's a look at the science behind this odd phenomenon.

How Termites 'See' the World

Termites are social insects. They live in colonies in which individual termites perform specific roles to benefit the community. Like ants and honey bees, social termites must communicate with other members of the colony to share important information. However, nearly all termites are blind and deaf, so how do they communicate with each other? The answer is they use natural chemical scents called pheromones.

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Pheromones have chemical signals that relay information. Termites secrete these communication compounds from special glands on their bodies and detect pheromones through the use of chemoreceptors on their antennae. Termites produce different pheromones for different purposes: to find mates, to warn other colony members of danger, to determine which termites belong to the colony and which don't, to direct foraging activities, and to locate food sources.

When blind termite workers wander out into the world, they need a way to let the other termites know where they are going, and they also need something to mark the way back. Trail pheromones are chemical markers that lead termites along a path to food and help them return to the colony once they've found it. Termite workers following trail pheromones march along the designated path, sniffing their way forward with their antennae.

Why Termites Follow Ink Trails

Termites occasionally follow trails that aren't produced by other termites if the substance contains compounds that mimic trail pheromones. Certain fatty acids and alcohols seem to confuse traveling termites, for example. Quite by accident (presumably), the makers of Papermate^® pens have managed to produce an ink that reliably mimics a termite trail pheromone. Draw a circle, line, or even a figure eight with one of these magic termite-magnet pens, and the termites will march along with your doodle with their antennae to the paper.​

Using gas chromatography, scientists have isolated a substance called 2-phenoxyethanol, a volatile compound that functions as a drying agent in the ink of certain ballpoint pens, and identified it as the likely termite attractant. However, 2-phenoxyethanol isn't present in all types of ink. Termites aren't inclined to follow trails of black or red ink, nor do they traipse along lines drawn with felt-tip pens or rollerball pens. Termites are brand loyal consumers as well. Their marked preference is for blue ink pens made by Papermate^® and Bic^®

Termite Ink Trails in the Classroom

Using ink trails is an entertaining and instructive way for students to explore termite behavior and to investigate how pheromones work. The "Termite Trails" lab has become a standard inquiry activity in many science classrooms. If you're a teacher interested in trying the "Termite Trails" lab, sample lesson plans and resources are readily available online.