Like amphibians, many insects have complex life cycles. Adults lay eggs on certain plants so their young can eat and grow quickly before changing into adults. Making this change is fascinating to watch:
- A female butterfly lays its egg on a plant.
- The egg hatches, and the caterpillar, or larva, comes out.
- The caterpillar feeds on plants. It grows a great deal during this stage. When it is fully grown, the caterpillar spins a cocoon on a branch or leaf and attaches itself to it. Inside the cocoon, the pupa, or chrysalis, forms the wings and legs of a butterfly.
- Finally, the butterfly comes out.
This transformation from larva to pupa to adult is called metamorphosis.
- Metamorphosis: the rapid transformation of a larva into an adult that occurs in some animals
- Adaptation: a genetically determined characteristic that enhances the ability of an organism to cope with its environment, such as the shape of a bird’s beak
- Camouflage: protective coloring that helps an animal blend in with its surroundings
- Notebooks and pencils
- Sweep nets
- Jars with holes in the lids
- Have students name different kinds of insects. Add others they didn’t think of. Make a list on the board.
- Discuss what they know about insects. Make a list of characteristics, adding any the students didn’t think of.
- Take students outside to look for, observe, and collect insects with sweep nets. Have them write down what they see.
- Back in the classroom, discuss their observations. Be sure to talk about each point below (bullet points after #6).
- Explain the life cycle of a butterfly, an insect they are familiar with. Have students illustrate it and/or act it out. Collect caterpillars, and bring them into the classroom. Put them in a container with sticks and leaves. Watch them metamorphose; release the butterflies.
- Have students draw pictures of insects on cards. Add these to the collection.
- Movement. Some insects fly; others crawl. Can you give examples of each?
- Coloration. Some insects are easy to see; others are hard to see. Why is this? Some insects have bright warning coloration. This tells birds, for example, to stay away: “Don’t eat me!” Other insects use camouflage to try and blend in with their surroundings so they won’t be seen by predators.
- Social relationships. Ants, for example, live in large colonies. A queen lays eggs her whole life. She has wings when she’s young, but loses them after the first time she mates. Worker ants are females who cannot reproduce. Their job is to collect food to feed the colony and defend the colony. Most of the ants you see when you look at an anthill are the worker ants. The large female ants are soldiers. They also defend the colony, and they go to other colonies to capture slaves. Like the worker ants, they cannot reproduce. There are very few males in the colony. They have wings, and their job is to look for a queen ant so they can mate. After they mate, they die. Termites also have a highly social form of organization, with a king and queen, workers, soldiers, and a few males. They like to eat wood and are very good decomposers, making the soil near their mounds fertile. When the queen termite dies, the mound is abandoned by the termites and taken over by other animals, such as dwarf mongoose and porcupines. Termite “swarmers” go to look for a new colony and will become the new king and queen of the colony. When it rains, swarmers fill the sky as they leave the mound. At that time, you can see many, many birds feeding on the termites. Bees are another type of insect that is very social. Each hive contains a queen, drones or males that reproduce, and workers or females that cannot reproduce. The workers feed the queen, guard the entrance to the hive, and collect nectar to make honey. They are helpful because they pollinate flowers as they collect the nectar.
- Communication. Bees communicate with each other, sharing information such as direction and distance to sources of pollen. This information is given in an elaborate dance.
1. Insects and Hunter
Talk about insects and how they defend themselves. One concept discussed above was coloration. Some insects have a bad taste to discourage predators from eating them. Still others sting their predators.
One student will be the hunter and must decide what kind of predator to be, while others pantomime an insect they have chosen. The hunter goes after the insects, and they must use their particular defenses to keep from being touched by the hunter. Tagged insects must sit down.
2. Caterpillar Walk
To demonstrate how animals use their senses to find their way, locate food, communicate, etc., place students in groups of 2 to 5, and blindfold them. A non-blindfolded leader will take them on a walk. Students walk in a line holding onto the shoulders of the person in front of them. They are taken to a location where they are asked to explore the area with touch, smell, and sound. Students are brought back to where they started and are asked to describe the area they explored. Teachers can then discuss how senses are used by animals by prompting students about animals’ needs and how they are met via different senses. For example, how does a predator find its prey? (By listening for its movements, smelling its smell).