Illinois Natural History Survey - University of Illinois

The Naturalist's Apprentice: Chemical Cues

Objective: to learn how insects use chemical cues to locate each other

Materials: multiple copies of Chemical Cues

Vocabulary: molecule, nocturnal, pheromone

Comments: Most organisms, both plants and animals, must periodically get the sexes together to produce the next generation of young. Insects have evolved any number of ways to do this, but one of the most interesting methods is demonstrated by moths. Female moths release a specific chemical into the air (called a pheromone) that can be detected by male moths of the same species. The males use their two antennae (often very feathery) to detect the chemical trail in the air and home in on the female. Some male moths, like the cecropia featured in Species Spotlight, can detect this scent trail up to a mile or two away! These chemical pheromones are very specific, and each species of moth has its own special chemical attractant.

 

Procedure:

1. Introduce the subject of pheromones from the above material and that found in Species Spotlight.

2. Distribute copies of Chemical Cues and have students find the correct chemical pheromone trail from the male to the female. Students should draw a line that passes lengthwise through each correct chemical molecule leading the male to his mate. 

3. Discuss additional ways in which organisms may use chemicals to alter the behavior of other organisms (i.e.,release smells to ward off predators, release odors to attract pollinators, use chemicals to mark territories).

 

Chemical Cues

 Moths use chemical cues, called pheromones, to help the sexes get together. Since most moths are nocturnal (active at night), this method is very efficient. Each species of moth has its own special chemical that is released by females to attract males. Locate the pheromone being released by the female gypsy moth and trace a path the male gypsy moth must follow (passing lengthwise through all the correct molecules of pheromone) to locate his mate.

pheromon.gif



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Subject: INHSPUB-00420
Last Modified 7/03/96



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