Letters to a Young Scientist

by Edward O. Wilson

Let me pause here to describe an easy way for you to smell an alarm pheromone yourself. Catch a honeybee from a flower in a handkerchief or other soft cloth. Squeeze the crumpled cloth gently. The bee will sting the cloth, and as it draws away it will leave the sting (which has reverse barbs) stuck in the cloth. When that happens, the immobile sting pulls out part of the bee’s internal organs. Let the bee move to the side, then crush the sting and the organs between two fingers. You will smell an odor that resembles the essence of banana. Its source is a mixture of acetates and alcohols in a tiny gland located along the shaft of the sting. These substances function as an alarm signal, and they are the reason other bees rush to the same site and add their own stings. Next, if the eviscerated bee hasn’t flown away, crush its head and smell that. The acrid odor you detect is from a second alarm substance, 2-heptanone, emitted by glands at the base of the mandibles. (Don’t feel bad about killing a worker bee.

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