Insect Design

Background

Over one thousand species of insects live in the greater Great Sand Dunes ecosystem. They live in the sand, soils, forests, rivers, lakes, grasslands, and on the tops of the mountains. Just about anywhere you go, you will find insects.

Because extensive fields of sand have been in this area for thousands of years, a number of insects have become specially-adapted to live in the sandy environment. Seven species of insects are known to be endemic to the dunefield and sand sheet ecosystems.

This lesson concentrates on Great Sand Dunes insects and their general external morphology. A 16-page workbook is available for students grades 3-5, and a 12-page coloring book is available for younger students. Find My Critter is a good follow-up activity for third to fifth grade students.

Insect Basics

Insects have three main body parts: the head, thorax, and abdomen. They have six legs. Most insects have compound eyes and antennae for smelling and feeling. Many also have wing variations for flight.

Insects belong to the invertebrate branch of the animal kingdom—"invertebrate" means animals without backbones. Insects have no endoskeleton (internal skeleton) but they have an exoskeleton (external structural covering). They are in the subgroup, arthropods, which are cold-blooded animals with jointed legs. Entomologists, who are scientists who study insects, think that we have discovered only about half of these important creatures.

The following background information is primarily for the extension activity.

Insect Mouth Parts

An insect's mouth parts have evolved and changed to allow different kinds of insects to eat in different ways. The head section of an insect has three pairs of mouth parts which have evolved to serve as teeth, tusks, tongues, tongs, talons, tweezers, chisels, pliers, claws, jaws, saws, and straws. In general, the first pair of mouth parts serves to crush, like teeth. The second serves to grasp, like tongs. The third set probes and tastes like a tongue. Therefore, insects possess three sets of modified jaws for specialized eating techniques.

There are two basic types of insect mouth parts, those adapted for biting and chewing and those adapted for sucking. Many insects have variations or combinations of these two.

Biting and chewing insects like grasshoppers, crickets, beetles, and cockroaches have two grinding mouths called mandibles. They are usually lined with teeth and move sideways. They also often have pinchers or mandibles that cut and tear off food. They can often have a second pair of jaws behind the mandibles called maxillae. Maxillae are used to push the food down the throat. Biting and chewing insects have lips. The upper lip is called the labrum and the lower lip is called the labium.

Sucking insects have adapted mouth parts to suit their eating habits. In insects such as the mosquito, the labium has become a grooved beak with four sharp needles called stylets. These are used for piercing and then sucking. The mandible has become a long sucking tube called a proboscis in butterflies and moths. Honey bee mandibles perform a combination of chewing and lapping. The housefly simply sponges its food.

In the larvae of the the Great Sand Dunes tiger beetle, the first pair of mandibles has developed into tusk-shaped pinchers. The larva lies at the base of its burrow waiting for a meal to pass by. Its tusks can snap shut like a trap, grabbing and stabbing its meal, usually another insect. The larva then drags its prey down into the tunnel where it uses its mandibles to eat at leisure.

Procedure

Step 1: For each student, prepare one copy of the Insect Workbook (grades 3 to 6) or the Insect Coloring Book for younger students. These printable Adobe Acrobat files are designed to be printed back-to-back, folded, and stapled in proper order. Page 2 is printed on the back of page 1, page 4 is printed on the back of page 3, etc. Use the diagram below to assist with production of Great Sand Dunes' insect booklets. You may wish to print each sheet out and then use a photocopier to collate the booklets.

Step 2: Discuss the concepts described above and provide each student one workbook or one coloring book. Older students will have the chance to invent their own insect. Provide students drawing and coloring materials.

Step 3: Once completed, post workbooks on a bulletin board so that students can see the variety of invented insects (booklet, page 14). Afterward, students who are interested may present their invented insect to the class. Be sure they describe how their insects' specialized parts are used in they way they live/eat.

Assessment

Completed workbook.

Extension

In this activity, students will try to use models of various insect mouth parts to gather 'food'. They will then discuss and evaluate each one to decide which one belongs to commonly found bugs at the sand dunes.

This activity is ideally done in groups of four. Up to eight students per group is possible, if turns are taken with the mouth parts. A set of materials will be needed for each group.

Materials for this activity: (mouth parts) tweezers, straws, clothespins, 1/2 to 1-inch pieces of sponge on a stick; one collection cups for each student; (food) torn and crumpled paper bag pieces, pop bottle filled with colored water, baby food jars with colored water covered with plastic wrap and taped, a shallow bowl filled with colored water, a rock-dirt mixture.

Procedure

1. Have each group sit in a circle around a pile of the different foods and give each student a collection cup and a mouth part. Discuss how the different mouth parts are specialized for chewing-crushing, sucking, sponging, or piercing-sucking.
2. Each student will have to collect as much food as possible and place it in their cups—liquid or solid. Demonstrate how to use the straw to pick up liquid and place it in a cup using a finger to hold the liquid in. Point out that only the piercing straw can be use to puncture the plastic.
3. Allow one minute for each 'eating' session, during which students use only their 'mouth parts' to collect as much food as they can.
4. Consider these questions with the students:
   Which mouth parts were best for getting which types of foods?
   Were the results consistent among the groups?
5. Compare the mouth parts for this activity with the ones described on page 13 of the workbook.

Extension activity adapted from Critters, by AIMS Education Foundation