Insects Lesson for Middle School Biology
This is the 23rd lesson in a series of 32 hands-on lessons covering middle school biology from a Christian perspective. This lesson focuses on insect anatomy and the introduction of beetles, bugs, and flies. I used this plan while teaching a 55 minute middle school biology class. Each lesson plan includes homework assignments and a variety of hands-on activities to make each lesson engaging & memorable. Use these fun lessons with your classroom, homeschool, after-school program, or co-op!
These lessons are written for a class that meets once a week. If your class meets 5 days a week, simply do this lesson one day a week and use the homework assignments (at the bottom of the page) for the work for the other days of the week.
1. Go over the homework questions from the book. (I give out tickets for students who volunteer to answer the questions.)
2. Quickly give an overview of arthropods and discuss insect anatomy.
- *My notes from what I went over can be found at the bottom of this lesson before the homework section.*
- I did go over them rapidly as we flipped through the pictures in the textbook.
- The students did not have to copy the notes or write anything down.
- I didn't only speak. I asked the students lots of questions throughout the time I was talking; for example, I asked them to name the 5 major classes of arthropods, name a major characteristic of an arthropod, tell me the 3 parts of an insect, etc.
Types of Insect Mouth Parts & Insect Orders
3. While going through the notes, when we discussed the variety of insect mouth parts, we paused for an activity. Each insect has a "custom-made" set of mouth parts designed to fit the food God planned for it to eat.
- Ahead of time tape a leaf to a Caprisun-type pouch drink. This will represent a flower filled with nectar. Pass one out to each student along with a piece of paper towel. Also have them take out their scissors. If desired, also pass out a party blower to each student.
- They should first use the scissors to rip off the leaf and cut up the leaf as if you were an insect that was eating up the leaf. Which insect has sharp jaws used tear up plants? (grasshopper & others).
- Use the straw to jab into the "plant" (juice pouch). Students can suck up the nectar. What insect might it be? (spittlebug & others)
- If this wasn't the nectar of a flower but was your arm & it was sucking up blood, what insect might it be? (mosquito)
- Allow student to blow out their party blower (if you gave one to each student) or simply demonstrate with one. Butterflies and bees have tongues like the party blowers. After they uncurl their tongues, they suck in nectar like a straw.
- Now crumple or fold up the paper towel, put it over the straw, and try to suck it up. House flies and some other insects have sponge-like mouths. If they land on something solid that they want to eat, they spit out an enzyme that dissolves the material and makes it liquid so that they can sponge it up for food.
You will need per student:
- Caprisun-type pouch drink and straw with a leaf taped to it
- piece of clean paper towel
- party blower (that blows out and rolls back up) (optional)
- pair of scissors (which students should have)
4. Go through 4 orders of insects. (The notes are below.)
- Have students look at the pictures in their books (or at PowerPoint slides) while quickly going through each type of insect. I asked lots of questions and shared personal stories while going through each order.
- Show any specimens, live or dead, that you might have. We passed around cicada exoskeletons and examined a housefly's mouth using a magnifying lens. You can also pass around ladybugs and show off maggots from rotting trash.
You will need:
- magnifying lenses (optional)
- insect specimens (live or dead) from the orders Coleoptera, Hemiptera, Homoptera (now a suborder of Hemiptera), & Diptera
Coleoptera: "Sheath-winged" = beetles
- hard forewings = elytra form straight line down back & front closely over body like shell = protective coverings for flying wings beneath them
- strong jaws & chewing mouth parts
- complete metamorphosis
A. Ladybug/Ladybird beetle
- differ in number of spots
- Whenever my kids find ladybugs, I tell them to put them on our fruit trees. Why? (They eat aphids - up to 500/day = control pests.)
- winter: groups huddle to hibernate - Who has come across a group of them indoors during the winter? Every winter the guest room of my mother-in-laws house is filled with ladybugs.
- Who has found these in your flour? We have!
- snout beetles with prominent rostrum = beak-like projection in front used to bore into roots, leaves, seeds, etc. – lay eggs in flour
- Granary = flour; boll – cotton
- My brother-in-law was stationed in Enterprise, Alabama. In the middle of downtown they have a monument dedicated to the cotton boll weevil. Why? It destroyed their cotton crops, which led them to pursue more profitable crops and businesses.
- one of few terrestrial bugs displaying bio-luminescence
- Who has caught these at night?
- whirl in circles on surface of pond
- 2 compound eyes above water & 2 compound eyes below water
- antennae rest on water to detect motion & helps avoid obstacles
E. Predatory diving beetle
- must take air with it so stores air in elytra (usually 20 minutes under water but up to 36 hours)
Hemiptera: "Half-winged" = bugs
- bug = piercing-sucking mouth part
- forewings have distinct halves: Front are hardened & back are membranous & form x over back (some don’t have wings)
- bedbug, chinch bug, squash bug. Stinkbug, water boatmen, backswimmer, giant water bugs, water striders
- Assassin bug – stick its beak into victim’s soft neck to paralyze it & then sucks out body fluids
- Stinkbug produces oily substance with bad odor
Homoptera: "Same-winged" - (now a suborder of Hemiptera)
- wings are same size, shape, & form
- rests wings on back in shape of a tent
- not all have wings
- piercing-sucking mouth parts to feed on plants
- incomplete metamorphosis
- most live on specific plants
- aphids, scale insects, mealybugs, leafhoppers, lac insect (of Asia produces shellac made into lacquer)
- cicada – lives underground as nymph for 13-17 years, tunnels to surface to spend 1-2 weeks as adult – males make noises - They are eaten throughout the world, particularly in China. The females are "meatier."
Diptera: "Two-winged" = flies
- mosquitos, flies, & gnats (2 plagues in Egypt)
- piercing-sucking or sponging mouth parts
- What is the deadliest animal in the world? The mosquito!
- 120 species in North America
- female bites to get blood needed for development of eggs
- mouth like a funnel with 6 sharp stylets to puncture skin
- saliva contains anticoagulant to prevent blood clotting & cause allergic reaction
- most males don’t bite & eat nectar & fruit
- carry many deadly viruses (encephalitis, yellow fever, malaria, etc.)
- hairs on feet carry microbes responsible for dysentery, typhoid fever, etc.
- female lays up to 150 eggs
- maggots – larvae of flies - Can be useful to forensic entomologists to determine quite a bit about the death of someone (how long they've been dead, places of trauma, etc.)
- could have 190 quintillion offspring in 5 months
C. Crane fly & midge look like mosquitoes but aren’t
D. Black flies or buffalo gnats
- bloodsuckers during day around ponds
- look like moss growing on rocks
E. Horsefly & deerfly
- Who has been bit by one of these? I have. It hurt for half an hour!
- like houseflies but larger
- adult females have nasty bite
Sketch the Life Cycle of a Mosquito
5. Everyone knows the life cycle of a butterfly. Let's look more closely at another well-known, but not as appreciated insect: the mosquito. Lead the students in sketching the life cycle of a mosquito by following this video by Ellen McHenry.
- I watched the video ahead of time and write out the notes she said while drawing on my sheet of paper. I used a new sheet for each drawing so that I had enough space to add the verbal notes.
- In order to significantly reduce the amount of time it took to draw the life cycle, we did not add shading to our drawings.
- In class I led the students step by step in drawing their own life cycle. I drew on the marker board while they drew on their papers.
- This was quite enjoyable. All the students were pleased with how well their drawings came out and everyone learned more about the mosquito.
You will need per student:
- the mosquito life cycle worksheet (from the above link)
Examine a hairy mosquito instar (larva)
6. (Optional) Allow students to look at a mosquito larva (instar) under a microscope. The kids loved seeing how truly hairy it is.
You will need:
- microscope with slide
- mosquito larva (instar) - If you don't have a mosquito larva, you might be able to substitute a different insect in its larva state as many of them are hairy.
My notes from the beginning of the lesson
I have included the introductory notes on arthropods and insect anatomy below (Activity 2 from the above lesson). After that I listed the homework assignment.
I. Armored Arthropods
- Phylum: Arthropoda: Insects, crustaceans, arachnids, centipedes, & millipedes
- 90% animals are arthropods = invertebrates with external skeleton & jointed appendages
- strong, lightweight exoskeletons composed of protein & chitin (similar to cellulose & starch) and provide protection, strength, & support
- Jointed legs & segmented bodies divided into distinct body regions
- body & exoskeleton are segmented & provide flexibility
- Molting – Outgrows & sheds exoskeleton – chitin splits & creature steps out
- Open system of circulation: Heart pumps blood (usually greenish, yellowish, or colorless) into large arteries, which open into body cavities, bathing internal organs with blood & blood flows back into heart without veins
- Some smaller crustaceans don’t have hearts & rely on body movements to circulate blood throughout bodies
II. Jean-Henri Fabre
- Entomologist – zoologist who studies insects
- research on bees, wasps, beetles, grasshoppers, & crickets
- importance of instincts & how insects behave together
- Christian & opposed Darwin’s theories
III. Six-Legged Fliers
A. Class Insecta – most varied & numerous of God’s creatures = 70% of animals & 90% of arthropods
- 1 million discovered & possibly 4-6 million more undiscovered
- only invertebrates that can fly
B. Physical Traits:
- 3 distinct body regions: head, thorax, abdomen
- single pair of antennae
- Most adults have simple eyes (1 lens) & compound eyes (up to thousands of lenses)
- Air enters through insects body in spiracles which lead to tracheae
- 3 jointed legs
- most have 1 or more pairs of wings
- Almost all begin as eggs (laid by hundreds or thousands)
- Direct development – some – hatch as mini-replica of parent & simply grow & molt
- Complete metamorphosis: (90% of insects) egg, larva (worm-like – grubs or caterpillars – hearty appetite & can cause extensive damage on crops), pupa (resting but lots of tissue reorganization – cocoon or chrysalis), adult (doesn’t molt or grow)
- Incomplete metamorphosis: dragonflies, mayflies, crickets, grasshoppers, locusts, cockroaches, & termites: egg, nymph (immature form of insect without wings & different body proportions – eats a lot as it molts), adult
-God has marvelously designed each insect for the kind of life that it lives. Not even the tiniest insect could have come about by chance.
A. Compound eyes
- Eyes are immovable & head has limited movement, but eyes allow it to see in several directions at the same time.
- Each eye is made of 24 - 28,000 six-sided sections fit in honeycomb pattern
- Gathers light, focuses it, & transmits through optic nerve to tiny brain
B. Simple eyes
- located between compound eyes on top of head, forming triangle points forward.
- detects light & shadow
- even more important than eyes for sensory
- wide range of shapes, sizes, & uses: moth = feathered & comb-like, June beetle = leaf-like, etc.
D. Sensilla (hair) – little sense organs
- on antennae & other places
- taste, smell, & hearing
- God custom-made mouth parts for what it eats
- divided by joints & number of joints sometimes used to distinguish between species
A. Lips: 2 lip parts & 2 pairs of jaw parts
- Labrum (upper lip) & labium (lower lip) – vary to suit type of food
- Labium has palps – feel & taste food
B. Mandibles – side to side jaws
- like teeth for chewing insects; needles for sucking insects (mosquito), sharp blades in horsefly
C. Maxillae + palp – paired jaws that assist mandibles
- chewing insect – hold food; siphon insects – long & slender like mandible; honeybee uses it to work with wax & pollen
- attached to thorax
- only adults have
- most have 2 pairs but some have 1 & some are wingless
- most insects grouped by design & structure of their wing, so orders end in Latin “-ptera” = wing
- divide families into genera & species by vein pattern of wings
- attached to thorax
- 3 pairs, each with 5 main sections
- variety: digging (mole cricket) – very large front ones for digging through soil; water insects with legs flattened into oars for paddling; crickets & grasshoppers have powerful hind legs for sudden jumping long distances; houseflies can walk on walls & windows because of tiny claws for grasping & hairy pads that secrete sticky substance; bees use legs for walking, working with wax, brushing pollen from body, & carrying pollen
- notice where legs attached = thorax & abdomen begins after legs
- 6-11 segments with pair of spiracles (more on thorax)
A. Respiratory system - intricately designed & complex
- spiracles – pump air through movement of wings & expansion & contraction of abdomen & trachea
- trachea widens into air sacs & divides into smaller tubes (tracheoles) which attach to cells
B. Final segment might have special appendage: earwig has ice tongs to spring body forward; female might have ovipositor to lay eggs
(Page numbers refer to the pages in A Beka's Science: Order & Design textbook.)
- Friday: Read pp. 340-347. Answer 6 questions of your choice from p. 347.
- Monday: Read pp. 348-357. Answer 7 questions of your choice from p. 357 and Tackle This on p. 353.
- Tuesday: Read pp. 358-362. Answer 3 questions of your choice from p. 362.
- Wednesday: Bring in something insect-related to show us and discuss with us in class. It could be a bug collection you own, pet crickets you raise, a butterfly wing or exoskeleton you found, mealworm cookies you baked, etc.
- Extra Credit: Sketch and identify 3 different insects that you find outside (not the same ones as last week). On each insect be sure to note the antennae, mouthparts, and types of legs. (You might need to capture it in a jar to inspect it more closely.) You can get another extra ticket for doing this for 3 more insects. (6 in total = 2 tickets)
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