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Using Insects in the Classroom
By Stephanie Bailey.  Adapted from "Six-Legged Science: Insects in the Classroom," by G.A. Dunn.
Updated 10/04 by Blake Newton, Extension Specialist

Insects are an excellent resource for science education.  Many insects are easily maintained in the classroom and can happily thrive despite being handled and kept in captivity.  The remarkable diversity in form and function of commonly found insects promotes interest and enthusiasm in observing the natural world.  Insects can also be used to model a variety of scientific principles. The objectives of this page are to give educators basic information about insects and ideas on how to use insects in the classroom.

Collecting Insects There are two types of insect nets: sweep nets (used for tall grass and shrubs) and aerial nets (for flying insects); the latter are sometimes called "butterfly nets."  These can be purchased from mail-order companies or made at home very cheaply.  Materials needed are an old broom handle or large dowel, wire coat hanger (unwound, then shaped into a"hoop"), duct tape, and either a pillowcase (for a sweep net) or netting remnant.  Many crawling insects can be captured without a net by using a small jar. Once caught, insects need to be placed in a killing jar or an observing container.  In either case, a clean, large mason jar or peanut-butter jar works well.  If you want to kill the insects and make a collection, use nail polish remover or rubbing alcohol to wet down cotton balls, and put them and some tissues into the jar.  The tissues give insects places to "hide," so they don't damage their wings when trying to escape.  Insects can also be killed by placing them in a freezer for 24 hours.  Collected and killed insects need to be pinned through their thorax, a little to the right of the midline.  High grade insect pins can be purchased from mail order companies or hobby stores.  Insects should then be placed in a sealed box, such as a cigar box or tight-fitting shoe box.  Serious enthusiasts may want to purchase professional boxes - either glass cases or a Schmidt box from a hobby store or mail order catalog.  Moth balls will protect specimens from scavengers. If you want to rear, maintain, or observe live insects, read our page on Classroom Mascots. Aquatic insect tanks are also easy to make and fun to observe.  Use a strainer or colander to collect aquatic insects.  Insects you might catch include: dragonfly immatures, mayfly immatures, whirlygig beetles, water striders, giant water bugs, diving beetles, water boatmen, and caddisfly immatures.  Many of these are predaceous, so supply some small feeder guppies or fairy shrimp, or else the tank will turn into a REAL test of survival of the fittest!  For more details on maintaining an aquatic insect habitat, read our page on Pet Bugs: Aquatic Insects. The best place to start catching insects is the school yard.  Insects are found around trees and shrubs, leaf litter, grass, and flowers.  You can also look under rocks and logs.  Some insects (flies and wasps especially) can be attracted with sugary or fruity liquids that are left outside in the sunshine.  Butterflies will form "puddle clubs" when tempted with small pools of sugary or salty water.  If you bury a bucket to the rim and fill it with gravel, then pour sweet and salty liquids over the gravel, you can have a permanent puddle for butterflies to use.  The foundation along the perimeter of the building, as well as bathrooms and supply rooms are suitable habitats for crickets, spiders, ants, and possibly cockroaches.  Field trips to a lake, forest, or park will offer even more opportunities for collecting insects. Activity: "Show and Tell" with Insects.  Have each student capture, identify, and look up information about an insect.  The students may want to develop an insect zoo and invite neighboring classes to attend.

Insect Diversity and Success There are well over 1 million species of insects.  They outnumber all other animals combined by more than 4 to 1.  There are more species of beetles than species of flowers.  Insects range in size from larger than the smallest mammals to small enough to crawl through the eye of a needle.  They have been around since before dinosaurs. Secrets for insect success include: Small size: insects can exploit many more niches (places in food webs) in a given area compared to larger animals Short life cycle: insects can develop in temporary habitats such as water puddles and decaying organic matter, and adapt to changing conditions much more rapidly than other animals. High reproductive capacity: as an example, an aphid has 50 offspring within its three week lifespan. Complete metamorphosis: insects with complete metamorphosis, such as beetles and butterflies, can exploit two separate niches in one lifetime. Exoskeleton: an exoskeleton protects insects from dehydration and damage. Flight: wings allow rapid movement to new habitats and food sources, and to escape from predation. Diversification: although insects all have the same basic structure, each insect species has adapted to its own particular environment. Insects have diversified in two ways: 1) Insects are present in every type of habitat except the middle of the ocean.  They are found on the tops of mountains and underground caves.  They thrive in deserts, rivers, fields and forests.  They have even been in space: Biosatellite II orbited the earth with fungus gnats, roaches, and wasps.  Insects are probably crawling through your house right now.  Some of the more highly specialized insects even build homes for themselves.  Caddisflies, as larvae, make cases in which they live.  A few species of wasps, aphids, midges, and psyllids can make galls (special swellings of plants due to feeding by the insect), which they feed on and receive protection from.  Many wasps, bees, and ants (order Hymenoptera) create nests, burrows, or social colonies.  Termites, which belong to a different order (Isoptera), also build large colonies and live socially.  Parasitoids live inside another insect until becoming adults.  Other insects live in or on the leaves, stems, or roots of plants. 2) Although they each have the same general body plan, different species of insects have developed changes in appearance and function of their body parts to adapt and survive in different niches. Camouflage allows some insects to blend into surroundings.  Certain butterflies, treehoppers, and caterpillars blend with their surroundings to hide from predators. However, some predators, like assassin bugs and praying mantids use camouflage for surprise attacks. ACTIVITY: CAMOUFLAGE EFFECTIVENESS. Materials needed: several colors of construction paper or pipe cleaners, at least 1 of which blends with grass (if outside) or with posterboard (inside).  Cut these into small pieces.  Spread the pieces randomly inside a marked area, either on grass or a sheet of posterboard, then have students pick up as many as possible within 10 seconds.  See how many and which colors are picked up. Other mechanisms used for protection include: Hairs and spines: Many caterpillars have hairs and spines. Some are "urticating" hairs, which sting, others prevent parasitoids from laying eggs in the caterpillars. Stingers: Wasps can sting repeatedly while honeybees only sting once.  Some wasps use their stingers to paralyze prey, then lay eggs and let their larva feed on the prey. Poison: Some insects feed on poisonous plants and accumulate the plant's poison (e. g. monarch gets its poison from milkweed).  Other insects have a mechanism to produce their own poisons (e. g. ladybug). Mimicry: Some unrelated poisonous insects share color patterns.  For instance, milkweed beetles and ladybugs are both red and black.  Both of these insects produce poison.  It is believed that a predator will learn to avoid all red-and-black insects if it feeds on one that makes it sick.  Sometimes, non-poisonous insects will mimic these color patterns as well, even though they are not poisonous.  An example: the non-poisonous Viceroy butterfly which mimics the poisonous Monarch butterfly. Discussion: The defenses that insects employ can be compared to those of more familiar animals: hairy caterpillars are like porcupines, bombardier beetles have a spraying mechanism similar to a skunk.

Insect Form, Function, and Development External Body Plan The integument or body wall of an insect is used for muscle attachment and protection from damage and desiccation. The integument is made up of two layers: the epidermis, which consists of living cells.  These cells secrete the outer layer, the cuticle, which is composed of protein and chitin.  Caterpillars and soft-bodied insects have cuticles that are mostly endocuticle, which remains flexible.  Hard-bodied insects have a harder exocuticle, with the endocuticle underneath. An insect's body is made of three main body parts: a head, thorax, and abdomen. The head is the center of coordination and feeding, with antennae, eyes, and mouthparts Form and Function of Insect Mouthparts - Different insects possess different types of mouthparts.  These mouthpart types can be compared with the functions of common objects:   chewing mouthparts (grasshoppers) - scissors   sucking mouthparts (stinkbugs) - turkey baster   stabbing mouthparts (deer fly, mosquito) - boxed drink straws   coiled mouthparts (butterfly) - party favor   sponging mouthparts (housefly) - dishwashing wand-sponge Some insects with stabbing mouthparts can transfer diseases.  This can be shown by first uptaking colored water with a turkey baster, let it out, then uptake clear water with the baster.  The clear water will become slightly colored.   The thorax is the center of locomotion, containing legs (1 pair per segment) and wings, if present (on the last two thoracic segments).  Front wings may be modified to very hard (beetles) or leathery (grasshoppers), and function as armor.  True flies (order Diptera) have a special adaptation to their second pair of wings, which have evolved into knob-like structures called halteres, which are used for balance. Observation: The Movement of Wings in Flight.  Materials: strobe light and large butterfly, moth, or roach.  Tether a large insect by gluing a thick string to its thorax, then lift the insect off the ground and allow it to flap its wings.  Adjust the strobe light until the movement can be easily seen and stopped.  Note the curve of the forward line of wings in downstroke and upstroke.  A note of caution: use of the strobe light with this experiment may bring on epileptic seizures so check with students or parents first! The abdomen contains reproductive structures, most of the spiracles (openings for breathing, also present on the thorax), and cerci, which are sensory structures, much like antennae.  All of these external structures can easily be shown with large grasshoppers. Internal Systems Insects have open circulation.  The only artery is the dorsal aorta, which pumps blood from the back of the insect up to the head. Respiration is not through the bloodstream.  Oxygen enters insects through their spiracles (holes on the side of the body) and branches out through a network of tubes into every cell in the body. Digestion proceeds from the insect's mouth through the esophagus, and into the crop, which is a storage site.  A valve called the proventriculus separates the crop from the midgut.  In some chewing insects, the proventriculus has hardened "teeth" which help to break up food stored in the crop.  In the midgut, an envelope called the peritrophic membrane protects the walls of the midgut while allowing digestive enzymes to enter and digested products to filter out and pass through the midgut membrane into the hemolymph.  The gastric caeca are large pockets on the anterior side of the midgut that allow adsorption of digested materials.  Malphigian tubules, located at the posterior end of the midgut, have a function similar to our kidneys, namely filtering water and wastes out of the bloodstream.  Fingerlike projections absorb waste particles and excrete them into the hindgut, which like our large intestines regulates osmotic (water) pressure as waste passes from the insect. The ventral nerve cord, like our dorsal nerve cord, brings messages to and from the brain. Reproductive structures in insects include ovaries, bursa copulatrix and uterus in females, testes, aedeagus in males.  Interesting mating habits include those of bedbugs (the male 'stabs' sperm into the female through her body wall) and dragonflies (males transfer sperm to secondary structures located on the second abdominal segment; to mate, males hook their cerci behind the female's head, then the female must curve her body underneath to collect sperm. This forms a "wheel"). Insects are cold-blooded.  Any activity depends on a certain amount of body heat.  Often, flying insects must "warm up" their bodies by flapping their wings before being able to take off.  In very hot temperatures, insects must find shade so as not to overheat.  Many insects, including moths, butterflies, and bees can funnel heat produced from flying into the abdomen, where abdominal spiracles and body wall allow heat to escape.  Dragonflies at rest modify their posture depending on whether they're hot or cold.  If hot, they position themselves upright to make as little surface area as possible exposed to direct sun.  If they are seeking warmth, they rest flat on a surface perpendicular to the sun's rays to get maximum exposure. Experiment: Cricket Thermometers. Materials: Male tree cricket, thermometer, ice in a bucket, hot or warm water in a bowl.  Count chirps per 15 seconds at several different temperatures (at least 3, preferably 5).  Use the ice to cool, then hot water to increase temperature.  Determine the lowest temperature that crickets chirp, and then graph chirps vs. temperature.  Later on, without using a thermometer, see what room temperature is by the number of chirps. (The sum of tree cricket chirps in 15 seconds plus 40 approximates the air temperature in degrees fahrenheit around the cricket.) Insect Development Insects grow by molting, as opposed to gradual development of humans.  Whenever an insect grows slightly larger, it must shed its skin.  Once insects become adults, they are unable to molt any further, and will not grow any larger. Metamorphosis: Insects have either Simple or Complete Metamorphosis. Simple Metamorphosis: Development proceeds from an egg to nymphs (which usually look like the adult, except for underdeveloped wings) to an adult.  Examples include grasshoppers and milkweed bugs.  Also called "incomplete metamorphosis." Complete Metamorphosis: Development proceeds from the egg to a larva, which is usually wormlike and does not resemble the adult insect.  When full-grown, the larva transforms into a pupa, then finally the adult.  The pupal stage is needed to develop the wings and other appendages such as antennae.  Examples of this type of development are butterflies and moths, beetles, wasps and flies. Observation: Insect Development.  Materials: Insects (milkweed bugs or hissing cockroaches will show simple metamorphosis, butterfly or moth caterpillars or mealworms will have complete metamorphosis), food, water, container.  Get eggs from a mail order catalog, then 1) count the number of molts and/or days till they become adults, or 2) measure head capsule and/or body length each day to see WHEN they molt, how much bigger they get as they molt, and how long in between molts. Observation: Butterfly or Moth Emergence. Collect several cocoons or chrysalis in spring or fall (if fall, pupae need to be kept cold to complete development). Hopefully at least one will emerge during class in the spring. Insect Classification or Taxonomy All organisms are classified according to a hierarchy:   Kingdom   Phylum   Class   Order   Family   Genus   Species This can be compared with the division of land in the United States. The largest grouping is a country, which is divided into states, then counties, towns, streets, and individual houses. Insects all belong to the Class Insecta.  These are further grouped into orders.  90% of insects belong to a few very common orders.  Common adult insects can be distinguished by looking at characteristics of their wings, mouthparts, and legs: Odonata: dragonflies and damselflies.  These insects have large, clear wings and chewing mouthparts. Orthoptera: grasshoppers and crickets.  The front wings of crickets and grasshoppers are leathery and these insects have chewing mouthparts and back legs which are large and adapted for jumping. Hemiptera: true bugs.  True bugs have sucking mouthparts, and the front pair of wings are half leathery, half membranous. Homoptera: aphids, cicadas, leafhoppers.  Homopterans have sucking mouthparts, and the front wings are either leathery or membranous (but not half and half, as with true bugs). Coleoptera: beetles.  Beetles have very hard or leathery front wings with no veins showing and chewing mouthparts. Lepidoptera: butterflies and moths.  These insects have coiled sucking mouthparts and scale-covered wings. Diptera: flies, including house flies, mosquitoes, and horse flies.  True flies have only one pair of functional wings, with the back pair modified into balancing organs called "halteres."  True flies have and piercing, sucking, or sponging mouthparts. Hymenoptera: bees, wasps, and ants.  These insects have two pairs of clear wings and chewing mouthparts. Observation: Comparative Study of Butterfly and Moth.  Capture a butterfly and moth, and put each in a separate jar. Compare similarities (number of legs, wings, mouthparts, etc.) and differences (colors, antennae, body, how wings are held at rest, etc.). Have students collect lots of insects (maybe working in groups) with the goal of getting representatives from several orders.  Ask students to try to classify each insect into the correct order by their own methods, giving their reasons for putting the insects in certain groups. Older students may be able to appreciate learning where words originate (e. g. "diptera" means two-wings, "lepidoptera" means scale-wings).  Much of the vocabulary in insect taxonomy can easily be explained based on characteristics of insects having a particular taxonomic name.

Other Classroom Uses of Insects Activities 1) Name "good" and "bad" insects and things they do (remember, in the natural world, there is no such thing as "good" and "bad."  Insects are only good or bad when humans label them as such!). Good insects: honey, wax and pollination from bees, silk from silkworms, pollination from many insects for fruit and alfalfa production, scent from flowers due to luring insects, beneficial insects which eat pests (ladybugs, praying mantids), medical cures and research (e. g. movie "Medicine Man"), fly maggots can be used to clean infected wounds. Bad insects: Less than 1% of insects are considered "bad."  Examples of pest insects include those that damage food (e. g. worms in apples, others feed on various crops); roaches, termites, houseflies and other household pests; those which sting or bite (wasps, bees, mosquitoes, ticks, fleas); insects that transmit diseases, especially mosquitoes, which transmit malaria and dengue fever. 2) Alphabug: Go around the room, with each person naming an insect or insect "part" that starts with each letter of the alphabet. More Experiments 1) Do honeybees prefer sugar to nutrasweet? Fill small, open containers with either sugar water or water mixed with nutrasweet (or any artificial sweetener). Place the containers near a bee hive or in a field where bees are foraging.  Have the students record the number of bees that visit each type of liquid.  Older students may want to do a statistical test like the t-test or chi square. 2) Can honeybees see & learn colors? Use a few colors of construction paper to represent "flowers."  Place a clear container in the center of each flower.  Fill one container with sugar water but use plain water for the rest. After a few minutes, the bees will probably start flying straight to the flower with the sugar water. If so, rearrange the flowers, to see if they still go to the right color.  Hint: bees can't see red! Demonstrations with Spiders.   Even though spiders aren't insects, they are closely related and make great subjects for classroom demonstrations. 1) How do spiders know when they've caught something in their web? This demonstration can show that spiders are able to determine when an insect gets captured in their web, and how large the prey is.  Tie a string taught between two fixed objects.  Have a student on one end not look but touch the string to feel vibrations (this is the "spider").  Have another student twang the string at the other end with different forces, and see if student #1 can tell the difference. 2) Do all spiders' webs have the same pattern? Visit and observe spider webs or collect several webs by first coating with talcum powder or spray gently with white spray paint, then attach the webs to black construction paper that has been sprayed with hair spray to make it sticky. Compare to see if all spiders make webs with the same geometry.  Students may fins that spiders that are of the same species build similar webs, but unrelated spiders may make very different webs

References and other good books: Berenbaum, M. Ninety-nine Gnats, Nits and Nibblers. Dunn, G. A. Six-Legged Science: Insects in the Classroom. Young Entomologists Society. Eyewitness Books: Butterfly & Moth (1988), Insect (1990), Amazing Beetles (1991). Hickman, P. M. Bugwise. Klots, A. B. & E. B. 1001 Questions Answered About Insects. Milord, S. The Kids' Nature Book. Russo, M. The Insect Almanac. Turpin, F. T. The Insect Appreciation Digest. The Entomological Foundation. Van Cleave, J. Biology for Every Kid. Other Entomology Resources Kentucky 4-H has detailed guides for insect collecting, identification, and pinning. These should be readily available from county 4-H offices.   County 4H agents may also be able to visit classrooms with activities and live insects borrowed from the University of Kentucky.  Owners of local pest control companies may also be interested in coming to a classroom and talking to students.  Pest control professionals are usually knowledgeable about insects, and they can also discuss the pest control business, which is unusual and interesting.

OTHER TOPICS     Classroom Mascots - how to keep insects and their relatives in the classroom.     Starting an Observation Honey-Bee Hive

Youth Entomology Resources | PRESCHOOL - ELEMENTARY
For preschool and elementary educational materials, please visit our adjacent site, KATERPILLARS.

Photos courtesy B. Newton and R. Bessin, University of Kentucky Department of Entomology.
Except "american cockroach" and "mealworm," courtesy USDA.