Why Do Termites Follow Ink Trails?

How Papermate® Pens Attract Termites

Termite.
A termite finds its way to food and back home by following pheromone trails. Getty Images/Dorling Kindersley

Ballpoint pen manufacturers don't seem keen on advertising a little known but well-documented feature of their products—they attract termites! Certain ballpoint pens use ink that termites can't seem to resist. Draw a line with an ink pen, and termites will blindly (literally, blindly) follow it across the page. Why do termites follow these ink trails? Here's a look at the science behind this odd termite phenomenon.

How Termites "See" the World

Termites are social insects. They live in colonies, with individual termites performing specific roles to benefit the community. Like ants and honey bees, social termites must communicate with other members of their colony to share important information. But nearly all termites are blind and deaf, so how do they communicate with each other? They use pheromones.

Pheromones are chemical signals that relay information. Termites secrete these communication compounds from special glands on their bodies, and detect pheromones using 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 tell the other termites where they are going, and they also need directions to return home.

Trail pheromones are chemical markers that lead termites along a path to food, and help them find their way back to the colony. Termite workers following trail pheromones will march along the designated path, sniffing their way forward with their antennae.

Why Termites Follow Ink Trails

Termites will occasionally follow trails that weren't produced by other termites at all, if the substance contains compounds that mimic the trail pheromones.

Certain fatty acids and alcohols seem to confuse traveling termites, for example. And quite by accident (presumably), the makers of Papermate® pens have managed to produce ink that reliably mimics a termite trail pheromone. Draw a circle, line, or even a figure eight with one of these magic termite-attracting pens, and the termites will march along your doodle with their antennae to the paper.

Using gas chromatography, scientists have isolated a volatile compound known as 2-phenoxyethanol in certain ballpoint pen inks, and identified it as the likely termite attractant. But 2-phenoxyethanol isn't present in all ink. Felt-tip pens don't seem to attract termites, nor do lines drawn with rollerball pens. Termites won't follow trails made by all ballpoint pen brands, but seem to prefer those made by Papermate® or Bic®. The 2-phenoxyethanol occurs in blue ink only, it seems, because termites aren't inclined to follow trails of black or red ink.

Termite Ink Trails in the Classroom

This termite behavior is a fun way for students to explore and 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, here are two sample lesson plans for the investigation: