INVESTIGATION 1:MEALWORMS

PURPOSEIN MEALWORMS, STUDENTS WILL

• Observe meal worms change from larvae to pupae to adults.

• Describe larval segments, legs, and other structures ofmealworms.

• Learn the three parts of an insect-head, thorax, andabdomen.

• Communicate observations of the structure and behavior ofinsects in words and drawings.

• Provide for the needs of living insects-air, food, water, andspace.

S,.ilAND,Life SdeJ,lce

SCIENCECONCEPTS .'·~"IIl;~~t~Ile~hair,iood, ,water,

andspac~.·• Insectshavecnaracteristic

structures' and behaviors;• the life<cyc:1eof the beetle is

"egg, larva, pupa, and' adult,which produces eggs.

• Live organisms need to betreated with care and respect.

Mealworms Under Glassby Mike Wood

Topic Area)bservation skills: unaided eyes, hand lens

Introductory StatementEach student willieam basic observational skills by observ-ing a mealworm, first with unaided eyes and then througha hand lens.

MathCountingMeasuring length, volume

ScienceUfe scienceUsing a hand lensVisual appearance of a mealwormStructure of a mealworm

Math/Science Process SkillsObservingSpecimen handlingComparingDrawing a specimen

MaterialsFor each student:

hand lensmealworm2 - 8-ounce clear plastic cups4 ounces CREAMOF WHEAT ® cereal (regular, un-

cooked)small piece of apple or potato2" x 4" paper stripmetric ruler

For storing meal worms:quart-size jar with wide mouth2 cups CREAMOF WHEAT ® cereal (regular, un-

cooked)raw apple or potato slice

For classroom mealworm home:gallon-size clear glass jar . -2 quarts CREAMOF WHEAT® cereal (regular, un-

cooked)

Key QuestionWhat parts of a mealworm can you see through a hand lensthat you can't see clearly (or at all) without a hand lens?

Background InformationLearning to make scientific observations is a basic

science process skill. Drawings and written notations areoften used to make a permanent record of an observation.

20 © AlMS NEWSLETTER

These records are important because human memory isprone to error and forgetfulness. Drawings and the accom-panying written notations are especially important to biolo-gists and anthropologists. Their recorded observations ofthe structure and behaviors of plants, animals, and humansare often collected in journals. A scientist's joumal may bethe record of years of observation and work.

An instrument such as a hand lens or microscopeamplifies the senses and extends the iimits of observation.For example, we can look at a drop of pond water with oureyes and determine ifit is clear or muddy in appearance, butwe have to use a hand lens or microscope to see jf the dropcontains any living organisms.

The observational and recording skills this activity helpsstudents to learn are these:

Specimen handling .... .Objects of scientific interest must be handled with

extreme careto prevent damage to the specimens. This isparticularly important for live specimens.

DrawingThere are two. types of drawings that are used by

sclentists. Throughout this activity we willrefer to the first ast.eal~c drawings and the second as ~l, ~ and lLnedrawings. .

A ~lisUc drawing is an identification drawing made toshow what the specimen "really looks like." For example,this drawing of a mealworm larva helps someone identifywhether or not a given specimen is a mealworrn.

Since making a realistic drawing of a specimen dependsupon the scientist's ability to draw, and this is often limited,

NOVEMBER 1992

realistic drawings for journals and textbooks are usuallymade by professional illustrators. Still, it is fun and goodpractice to try to make realistic drawings.

The inability to make realistic drawings does not keepthe scientist from using drawing to record part of anobservation. An oval, box, and line drawing is a simple data

\_- -- ~ --<1[awing.It is used to record quantitative information suchas the number of d se ments as well as therelative position of parts of the specimen. For examp e, thisdrawing of a mealworm records the fmportant features ofmealworm structure as seen through a hand lens; it can bedone by almost anyone.

~Information such as the date and time that the obs~rva-

ti.9nwas made are recorded in writing; these are importantparts of the observation and it is important that they are~l1en. Any special conditions such as ffle weatherconditions, the time the observation was made, and wherethe observation was made ("under a rock", "on the table",etc.) are noted as part of the observation. Qualitativeinformation about the specimen, such as color or smell,arealso noted, The following is a sample of a journal record ofan observation made on a mealworm:

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Management1. When buying mealworms at your local pet store, ask for

some of the eggs, pupa, and adult beetles.

NOVEMBER 1992

2. Decide how much time you will spend observing themealworms, whether you are only going to do thisactivity' or observe the whole life cycle which takesseveral weeks. Decide how you are going to manage themealworms. One strategy is to give each student amealworm in a plastic cup half-filled with CREAMOFWHEAT®; the student keeps it on the desk throughoutthe time rnealworms are observed (or throughout arnealworm growth cycle). A second strategy is to keepall the mealworms in a large classroom mealwormhome and distribute them (in cups) as needed forobservations. Ifyou choose to have students keep theirworms individually. be sure to label the cups with theirnames. and add a small piece of raw potato or apple toeach cup as is done in the classroom mealworm home.With either strategy. discuss and decide upon rulesregarding when the mealworms are to be handled andobserved.

3. To make the classroom mealworm home. pour theCREAMOF WHEAT® into the jar. Other mediums suchas chicken mash or bran flakes may be substituted, butcheck to see they have not been fumigated in process-ing. Add the raw potato or apple to the container toprovide all the moisture the meal worms willneed. (Donot cover containers. Mealworms will not crawl out ofthem.) Keep the container in a cool. dark location. Thiscontainer will suitably house the mealworms through-out their life cycle. A mealworm takes several weeks toprogress from the larva (mealworm) stage through thepupa stage to the adult beetle stage.

raw apple or potato slice

.Ji~1.bd~~~"..mealworms

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A Good Mealworm Home

You may choose to have students observe each devel-opmental stage of the life cycle of a mealworm. This willprovide good practice for students' observational skills.

Procedure1. Discuss and demonstrate to students the correct way for

them to handle and observe their mealworms. Using thethumb and forefinger to pick up and grasp the meal-worm is not a satisfactory technique. as it is easy toapply too much pressure. In this activity. a rectangularpiece of paper is used to pick up, move, and otherwisemanipulate the meelworm. The tips of pencils can also

(Please see MEALWORMS. page 25)

© AIMS NEWSLETTER 21

7'- /7

When -the adult comes out of the, pupa rose it is white.It gradually turns broll>n o.nd fino/ly black. The adult hasWi t"lgs blAt cannot fly. 1+ can hop o.bout 10-/2 em. Theo.duItbeetl e lives on ''I G few months. The femalern~v lay up to 500 eggs before it cli es, o..nd +he,life cycle storts all over" CUjoin.

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Meal wormS are CAsuolly folAnd in dark darr"p pkicec.They are 5Caven9~rs LUho li~e TO eat ro-tting grain andcereal. They wdl eat ~al n, cereal, flou.r J Dr-an J b.--ead,cra.ckers, meo+ sCro..ps) :Feo.-the~ and. +he bodies ofdead. insec+t; .

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ore friends, it's time io measure u.p."

-1 M~mea/worm measures mm.

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Meal worms have 0. 4 stagelife c~cle. The~ begin as tjn~ eggsthat we can't sec. the secondstage is fhe larva or mea/wormstQge. Next fhe~ begin fheirmeta morpho6is and become Q

sleep~ pupa. Final! ~ -the~ become-Ct black beef/e. Cthe ad u It stage).

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Observation: Sense used:l.

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which sense did ~ou use rrost? _

Now, use other senses ..'Observation : ~nse used',

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