FOCUS: As insects develop from eggs to adult, they undergo metamorphosis, their bodies changing dramatically as they mature. Most insects go through complete metamorphosis with four distinct life stages: egg, larva, pupa, and adult. Other insects go through simple metamorphosis with only three stages, changing from egg to nymph to adult. These tiny animals must find partners to reproduce, and they use a variety of signals to find and attract mates.
Objective: To begin to explore and ask questions about insect life cycles.
Give a variety of insects in various stages of their life cycle in small jars to children to examine in small groups, and ask what they notice and wonder about them.
Materials: a variety of live insects in various stages of their life cycle collected in small jars, magnifying lenses.
PIECE IT TOGETHER
Objective: To observe and compare the life stages in a variety of insect species, looking for patterns and sorting by type of life cycle.
Ahead of time, mount each Metamorphosis Puzzle on a different colored backing. Place two different puzzles on each of three tables. Have the children work in small groups with an adult, sending each group to one of the tables. Now hand out a puzzle piece to each child and have everyone find the other pieces that complete their puzzles. Do all the insects have the same number of stages in their life cycles? Is there a pattern? (Some have three stages and some have four.) Read aloud or have the children read the Puzzle Stories about the insects in their puzzles. Have each group share one interesting fact about their insect with the group. You may have children rotate through the other stations to see and do other puzzles, time permitting.
Materials: Metamorphosis Puzzles mounted on different colors of cardstock, Puzzle Stories.
PUPPET SHOW “Frequent Flyers”
Objective: To compare the life cycles of insects with simple or complete metamorphosis.
Perform the puppet show, or have a group of children perform it for the class. Afterward, ask questions to review the key details and vocabulary in the story. What do we mean by “metamorphosis?” (Change in form.) How many different stages are there in the life cycle of a grasshopper? (Three – egg, nymph, adult.) What is this kind of life cycle called? (Simple metamorphosis.) How many different stages are there in the life cycle of a butterfly? (Four – egg, larva, pupa, adult.) What is this kind of life cycle called? (Complete metamorphosis.)
Show the Simple Metamorphosis and Complete Metamorphosis diagrams to review and compare the two life cycles. Point out the characteristics common to adult insects: six legs, three body parts, antennae, wings (generally), hard outer skeleton.
What are some differences between a nymph and a larva?
• Nymph looks like a smaller version of the adult, with six legs, eyes, antennae, three body parts, has wing buds but no wings.
• Larva looks very different from the adult, often has no legs or may have additional pseudo-legs, has no wings or wing buds, may or may not have any eyes or antennae, may or may not have three defined body sections.
Materials: puppets, script, stage, Simple Metamorphosis diagram, Complete Metamorphosis diagram.
LOOK AND LISTEN
Objective: To sit quietly, observing insect behavior on the school grounds.
Take children outside and find them spots to sit apart from each other, preferably where there is some vegetation like grasses, bushes, or trees. Ask them to sit very quietly, noticing insects or evidence of insects on leaves, stems, flowers, or on the ground. After a few minutes, call them back to a circle to share observations. What insects or evidence of insect activity did they notice? Why might insects be on or near the plants? (To feed on them, look for prey, lay eggs, etc.) What questions do they have about the insects they observed?
Materials: optional: plastic bags to sit on if ground is wet.
INSECT STAGES SAFARI
Objective: To collect and observe insects, looking for evidence about their life cycles.
Provide each child or pair of children with a small jar in which to collect an insect. Ahead of time, explain some guidelines about collecting insects. Each child may find and collect an insect in their jar. They should be careful not to hurt the insects, and they should avoid collecting bees, wasps, and hornets that might sting. It’s best not to collect moths or butterflies as their wings could be damaged by fluttering in the jars. Children should look for eggs, larvae, and pupae also, but they should not collect these stages. Instead they may draw them or photograph them in place, or mark the plant they’re on with yarn to show others. One method for finding insects in shrubs or tall weeds is by placing a white sheet on the ground and shaking or thumping the plants vigorously over the sheet. Help every child to catch an insect and then gather the children together to compare their finds. Which ones have wings that you can see? Do any of the specimens look like they might be nymphs (with short wing buds rather than fully formed wings)? Which of the different insect stages (egg, larva, pupa, nymph, adult) did they find?
Optional for a rainy day: Collect insects (different stages, if possible) ahead of time and bring them to the classroom in jars. Spread out a white sheet and have children kneel around the edge with bug jars. Gently release the insects onto the sheet. Have children observe movement and physical characteristics of insects, then catch some in jars and pass around for a close-up view. Have each child pick one for their journal entry.
Materials: for each child or pair of children: small bug jar or baby food jar with lid, magnifying lens; optional: yarn or colored pipe cleaners, small (pillowcase-sized) pieces of old white sheet; optional for rainy day: old white sheet, live insects collected ahead of time.
JOURNAL ACTIVITY and GOODBYE POEM
Objective: To record observations about insects in different stages of their life cycles.
Provide students with science journals or the Insect Stages Safari card and have them draw a large (3”x5”) picture of their insect, so they can show all the details. Have them consider whether it is a larva, nymph, or adult. Have children share their journal entries in small groups, and pass the insects around for all to see. What are some questions they have about their insects?
Before returning insects to the places where they were found, have children hold their jars (closed) and recite this goodbye poem.
I’m glad you shared this time with me
But now I’ll gently set you free
So you can hop or crawl or fly.
It’s time for us to say goodbye.
Now have them take their insects back to the place where they were found and gently release them.
Materials: for each child: science journal or Insect Stages Safari card, clipboard, pencil, magnifying lens; copy of Goodbye Poem.
UPPER GRADES CHALLENGE: Insect Stages Survey (Grades 5-6)
Objective: To conduct a survey of insects on the school grounds, looking for evidence of different life cycle stages.
Divide the class into small groups and assign each to a different part of the school grounds so that all areas will be covered. Have the students look in every nook and cranny for insect eggs, pupae, larvae, nymphs, and adults. School gardens, tall grasses and weeds, flower beds, and around building foundations are some good places to look. Use sweep-netting (sweeping an insect net just above the tops of tall weeds) to catch flying or hopping insects. Shake shrubs and weeds over a sheet to dislodge insects hiding in them. Have students keep a tally of adults, nymphs and larvae, pupae and eggs they find in their area. Have them find and examine one specimen closely, using the Insect Stages Study sheet as a guide to their observations. If time permits, the students may wish to study and answer questions about several different specimens. Afterward, compare their tallies with other groups. Which stage was the most common and why might that be?
Materials: Magnifying lenses, bug jars, Insect Stages Study sheets, clipboards, pencils; optional: insect nets, pieces of old white sheets.
Objective: To model how insects use different signals to communicate with each other.
Every kind of insect must find a mate in order to be able to lay eggs and produce young. How do tiny insects find each other? Different insects depend on sound, sight, or smell to find or attract a mate. Children will model the behavior of fireflies, which use light signals to communicate, and crickets or grasshoppers, which use sound.
Flash Codes: Firefly males produce a light in their abdomens which they can flash on and off to signal to females. Each species uses a different pattern of flashes for identification. To model this behavior, assign each child a number – one, two, or three – by handing out cards with these numbers written on them. Have children make a fist in the air and then make a flash by putting up one, two, or three fingers, depending on their number. Have them flash their number over and over while milling around and seeking others with the same number. When they find a match, they should stand side by side and cease flashing.
Sound Codes: Crickets and some grasshoppers produce a sound by rubbing the hardened edge of one outer wing against a row of pegs on their other wing, while grasshoppers rub a wing against a row of pegs on their back legs. This is called stridulation. Each species has a distinctive song that the female can recognize. Hand out a Cricket Song card to each child. Assign one group (based on card color) to be the singers (males) and one to be the seekers (females). At your signal, the singers should say or sing the words on their card, repeating the song at intervals, while the seekers look for someone singing their song. With younger children, pick only two or three of the insects to mimic and practice their songs ahead of time with all the children before handing out cards and assigning singers and seekers. When they find a match, they should stand side by side and cease singing.
For older children, do both Flash Codes and Sound Codes at the same time, to simulate insect activity on a summer night.
Materials: small cards with a number 1, 2, or 3 written on them; Cricket Song cards, two copies on different colored cardstock.
Objective: To reflect on insects and the stages in their life cycles.
Ask the children to complete this sentence: “My favorite discovery about insects is _____.”
A STEP BEYOND
Act It Out: Have children do charades of different insect life cycle stages and have classmates guess the stage.
Favorite Insect: Have children research their favorite insect to find out more about it. What kind of life cycle does it have?
Daily Survey: Pick a place to check each day for insects, and use a camera to keep track of insects found and changes in their stages over a few weeks. Vegetable gardens are good places to look for insects in different stages.