An Ant’s Nose Knows by Annie Brennen illustrated by David Besenger Ants have and need B.O. (Biological Odor) How can ants work together to build ant hills or drag home food that is hundreds of times their sizewhen they can’t even talk to one another?    Ants and many other insects have a special communication system that relies on their noses and combinations of different chemicals. These chemicals, called pheromones, are like perfumes that have the power to inspire a certain behavior or response. All ants make pheromones and release them from glands located on their bodies when they need them. In other words, when an ant wants to get something done, it makes a stink! Pheromones help ants find mates, signal danger to the colonyand tell other ants where to go and how to get there. People usuallycan’t smell these ant pheremones, but they send clear messagesto other ants. Some pheromones create what is called a "releaser effect"that produces a direct and quick response. It makes other antstake action immediately. For example, an ant might release analarm pheromone to tell other ants to get out of the way of anapproaching lawnmower. Other pheromones produce a "primer effect" that preparesor primes other ants for action, getting them in th e mood. Thesepheromones are useful when ants are thinking about mating. I like the way you stink  Ants give off some pheromones that affect only ants of theopposite sex. These pheromones help to make sure there will belots of baby ants in the future. They are so powerful they caneven attract a mate from a distance. Stay away! or Come here! Some pheromones act like fences, keeping out unwanted foreignants. The smells also mark territories and help keep a comfortabledistance between colonies. These pheromones also can work as alarmsto warn ants about a threatening situation. Other pheromones signal ants to come together. In some casesthey act like a huge dinner bell to get ants to assemble at afood source. The pheromones also might call ants together to helpbuild a colony, work that requires lots of help and cooperation. They are tiny, but ants live in incredibly organized communities.Without the help of a spoken language, they keep thousands ofmembers working together. This amazing organization is possiblebecause of invisible pheromones. These nose-to-nose chemical messengershelp ants maintain their complex communities. Smell me? Help me! Pheromones also can signal ants to evacuate a dangerous areaor defend their territory. If one ant sees a spider, it will releasealarm pheromones that will alert all the other ants. Alarm pheromones are released into the air, where they expandto create a large cloud of smell. The smell is stronger closeto the center of the cloud, but the outer region has fewer chemicalsand the smells are not as strong. Ants can tell by the intensityof the smell how near danger is. Ants also release alarm messages when they are distracted fromtheir work for any reason, like by the heavy foot of a human walking.

Click to Enlarge A wood ant strikes a defensive pose after detecting an alarm pheromone with its antenna "nose." It is now ready to spray formic acid from its abdomen onto the attacking metaphid jumping spider.     Click to Enlarge       Click to Enlarge