Background

Did you know that there are many more kinds of insects on earth than any other kind of living creature? It's hard to imagine, but 95% of all the animal species on the earth are insects! Millions of insects can exist in a single acre of land!  Scientists have discovered over one million species, and they think that there might be ten times that many that haven't been named yet!

They are divided up into 32 orders, or groups of insects. The largest order is the beetles (Coleoptera) with 125 different families and around 500,000 different species. In fact, one out of every four animals on earth is a beetle. Scientists estimate that 10% of the animal biomass of the world is ants, and another 10% is termites. This means that 'social insects' probably make up an incredible 20% of the total animal biomass of this planet!

Insects eat more plants than all the other creatures on earth! They are also so important in the breakdown of plant and animal matter, that without them, we would have a world covered with dead plants and animals! In addition to all of this, insects are a major food source for many other animals.

Insects can live in many diverse and even harsh environments. They are even found on Antarctica! The oceans are found to have the least diversity of insects with only 4 groups. Scientists are not sure what the reason for this lack of biodiversity is. Some theories are the saltwater makes it difficult for insects to thrive. Another theory is that insects have mainly evolved with flowering plants on land and have never really returned to the oceans. There is a larger diversity of insects found in the desert compared to the ocean. In forests, insects play a huge role in helping recycle nutrients on the forest floor. Insect larvae are responsible for recycling nutrients in the grasslands. In the tundra and wetlands, insects play seasonal roles in being huge amounts of food sources for migrating animals.

All insects must have:

•    3 body parts - a head, thorax, and abdomen
•    6 jointed legs
•    2 antennae to sense the world around them
•    an exoskeleton (outside skeleton)

If all four of these things are not true, then the animal can't be called an insect! Spiders are not insects because they have eight legs and don't have three body parts. Centipedes and millipedes have way too many legs to be called insects! Most insects have one or two pairs of wings, but wings aren't necessary to be classified as an insect.
 

Insects have 3 main parts: head, thorax, and abdomen.
 

The head is used mainly for eating, sensing things, and gathering information.  Insect mouthparts have evolved for chewing (beetles, caterpillars), piercing-sucking (aphids, bugs), sponging (flies), sucking (moths), rasping-sucking (thrips), cutting-sponging (biting flies), and chewing-lapping (wasps). That's a lot of ways to eat! ?All insects have two antennae that they use to sense the world around them. Whether their antennae are short, long, thick or thin, insects use them to feel, smell, and even taste!

The thorax protects the body and gives support for the three pairs of jointed legs and, on many insects, for one or two pairs of wings. The legs may be adapted for running, grasping, digging, or swimming.

The abdomen contains the organs used for digestion and reproduction.
 

Insect Growth and Development (Metamorphosis)

Insects usually go through four separate life stages: egg, larva or nymph, pupa, and adult. Eggs are laid one at a time or in masses, in or on plants, or even inside another insect! Eventually a larva or nymph emerges from the egg. There are usually several larval or nymphal stages, called instars. During each stage the nymph grows larger and molts, or sheds its outer skin before the next stage. They grow the most during the last one or two instars, or stages. All the growing happens during the larval or nymphal stages. The eggs, pupae, and adults don't grow in size.

(Note:  all background information taken directly from: http://www.ivyhall.district96.k12.il.us/4th/KKHP/1INSECTS/buginfo.html.  To find out more cool information check out this site!)

 

Attention Grabber

Ask students to brainstorm with their partners and create a list of animals. Give students 1 minute to see how many animals they can come up with. Create a master list by having students read off animals from their list that have not already been said.  (They will have quite a lot!) Using the pie chart (See attached) for a visual (with 95% insects, and 5% other animal species), show the students that most of the animals on Earth are insects!!  In this lesson, we’re going to learn about insects, where they live, and what they look like- up close and personal.

 

Vocabulary

Insect:  a small animal that must have 3 body parts, 6 jointed legs, 2 antennae, and an exoskeleton
Thorax:  the middle section of an insect
Abdomen:  the usually larger, lower section of an insect
Aspirator:  a device used to catch insects humanely
Biodiversity: is the variation of life forms within an ecosystem, biome, or for the entire Earth.
Environment: a term that encompasses all living and non-living things occurring naturally on Earth or in one region.


 

Introduction

Introduce the different parts of an insect through a large picture showing the labeled parts. Include the key points that make it a “true” insect: exoskeleton, 2 antenna, 3 body parts (head, thorax, and abdomen), and 6 jointed legs. Have students learn these parts by making hand motions and saying the words out loud (make antenna, point to the 3 body parts, have them do a little dance for their legs, etc..). First, students are going to study insects “up close and personal” by creating a scientific tool called an “aspirator” (or “pooter”).

 

Garden Activity

Part 1 Making an Aspirator

•    To make an aspirator, also known as a pooter, you will need:
o    Jar with a lid (the lid must have 2 holes)
o    Tubing (rubber tubing works best)
o    Small screen (panty hose are a great, cheap option)
•    See the picture below to help build the aspirator. 
•    Be sure to place a small screen (or panty hose) between the hose that will be used to suck on and the jar!  (If there is no screen, students may swallow the bugs!!!!)
•    Note that the size of the tubing will limit the size of insects that can be captured. 
*A clear plastic jar is ideal to use. If this is not available, you could also use just the cardboard tube of the toilet paper roll. In this case, the tubing will attach on one end and the tubing used to suck up the insect would be attached to the other end. Either masking tape or clay can be used to attach the tubing to the cardboard.
** Parent help can be ideal for this part of the activity.

Part 2 Bug Collection and Comparison
 

•    Brainstorm with the students possible areas that would be good to collect bugs.  Good areas to look are under rocks, under tree branches, bark, wood chips, along fences, and near compost.
•    Using these areas, choose two areas to compare.  Split the class into two groups.  (Note:  this can also be done using two different environments.  E.g., light areas v. dark areas, wet v. dry) 
•    GO COLLECTING!!
•    Give students magnifying lenses to examine the insects they caught.  Have students write descriptions or draw pictures of their findings. Students should also record the number of insects they find in their area! (See attached “Bugs, Bugs, Everywhere!” student handout). Be sure students include exactly where they found the insects so they can return them to their homes.
•    As students examine the insects, explain what is required to call an animal an insect.  (See Background section above)
•    Release the insects back to their appropriate homes. 
•    As a class, compile the data of the two areas.  Compare these results. 
•    Create a line graph using the numerical data.  The type of insect on the X-axis and the number of insects on the Y-axis.  Each area will have a different line color. 
•    Have students make conclusions based on the graph. 

Part 3 Bug Diversity

(Optional. For time, this can be integrated into part 2).

•    Have students keep track of how many different the insects they found. Divide students in groups of 4. One person is the recorder, two are “lookers”, and one person helps the recorder. Students can share roles to help share the workload.
•    Each group is assigned a specific area. “Lookers” will use the aspirator to collect insects and place them in a collection box. Ask them to remember where they found each insect. The “Sorter” will help the “Recorder” write down how many insects of each type they found.
•    Each group will work on this project for about 10 minutes. They can switch roles throughout the process.
•    Afterwards, each group will create a bar graph to show the different insects and how many they found. The X-axis can show the different insects. The Y-axis will show the number of how many of each insect they found.
•    Have each group share their results with the class.

 

Wrap Up & Assessment

•    As a class, have students create an ABC “Bug Book”. Together, come up with insects for each letter in the alphabet. Each student will create one page of the book by selecting an insect.
•    Have students present their insects in front of the class. Model and be specific about the information you’d like each students to share.


 

What’s Next?

•    Visit a butterfly garden!  Or, make your own butterfly garden at their school!
 

Download Materials

Student Worksheet