Say it with Scents (FBCEC)
Many animals communicate with chemicals called pheromones. In this activity, participants will explore how insects use pheromones. This “smelly” activity will challenge participants to identify scent-marked trees as well as a collection of mystery scents.
8 - 12
Indoor or outdoor classroom
Fred Berry Conservation Education Center, Yellville, AR
Education Program Coordinator, 870-449-3484
45 minutes - 1 hour
Suggested Number of Participants:
Up to 24
- Identify trees or other landmarks that have been “marked” with a scent.
- Identify mystery scents.
- Learn ways insects use chemical cues.
- Understand the importance of studying chemical ecology.
*See glossary for definations
Items for peppermint beetle activity (“Project Learning Tree” curriculum, pages 23 - 25)
Ant farm, if available, and a “guest” ant
Various scented oils, orange, lemon, etc.
Insects “smell” with their antennae. The chemicals (which produce an odor) attach to special receptors on the antennae. Insects use these chemical receptors to find food, a mate and a place to lay eggs. For example, worker bees use their sense of smell to locate food, and drones use their sense of smell to recognize the queen bee’s pheromone. Worker ants leave a scent trail when they find food, but if the trail is disturbed, they become confused. Social insects, like bees and ants, recognize others from their colony by their scent.
- Begin by discussing the sense of smell. Ask participants how they use their sense of smell. What would it be like if they lost their sense of smell? How is sense of smell related to taste? How does food taste when they have a bad cold or stuffy nose? What are some pleasant smells? Some unpleasant ones?
- Give examples (from above or others) of the way insects use their sense of smell. (If an ant farm is available, drop in a “visitor” ant and observe the behavior of the resident ants.)
- Next, conduct the activity peppermint beetle in the “Project Learning Tree” curriculum guide, pages 23 - 25.
- After conducting peppermint beetle, discuss the importance of research in insect chemical communication. As scientists understand how these chemical senses work, they can make safe pesticides specified for one pest that won’t put indiscriminant toxins in the ecosystem. For example, if a scientist can block the sensory receptor of an insect with a substitute chemical, it won’t be able to find its host animal or plant. Another way to control pests is to block the receptor for pheromones so the insect cannot find a mate.
- To illustrate, blindfold a volunteer and let them smell an orange, then two or three strong colognes or perfumes. After the volunteer smells the perfumes, have them distinguish between an orange and a lemon or two other similar smells.
- Wrap up by giving each participant a film canister containing a cotton ball moistened with an aromatic oil (rose, peppermint, lavender, etc.) There should be only two or three scents used. Instruct participants to imagine they are social creatures that must recognize others from their colony. See how long it takes for them to collect into their groups.
- Describe pheromones and how insects communicate with them.
- Explain how insects use their antennae.
- How can humans use insect pheromones to control insects?
Antenna (insect) – a moveable segmented organ of sensation on the head of insects
Chemical communication – communication by smell, especially by pheromones
Drone – the male bee that has no sting and gathers no honey
Ecosystem – plants and animals interacting with each other and their physical environment
Pesticide – synthetic and sometimes biological substance used to kill or contain pests
Pheromone – chemical produced by an animal that stimulates other animals of the same species to behave in certain ways
Receptor – a nerve ending sensitive to stimuli (extracellular signals) that can convert them into nerve impulses (intracellular effects)
Scent – a pleasant or unpleasant odor
Social insect – insect species that live in colonies and manifest three characteristics: group integration, division of labor and overlap of generations; examples include termites (Isoptera), ants (Formicidae) and various bees and wasps (Hymenoptera)