INSECTS

Introduction

Insects have for a long time been known as pollinators, honey producers, vectors, food and for beauty. Insect populations and their variety can tell us how important they are to the environment. Their
physical features and behaviour give an idea of the role they play in the lives of man, plants and other living organisms. The insects that we interact with regularly are the housefly, cockroach, mosquito, worker bee, and butterfly and soldier termite.

Do you remember which phylum and class these insects belong to?

External Features of an Insect

All insects have a head, thorax and abdomen. These parts bear other structures that enable the insect to function normally and live well in its environment.
Activity 4.1: Observing and drawing the back (dorsal) view of a cockroach
What you need
I) Freshly killed adult cockroach
ii) Notebook
iii) Pencil

Caution
After completing the activity, WASH your hands thoroughly with CLEAN WATER and SOAP
Why should you do this?

The Head of an Insect

The head of an insect bears antennae, mouth parts suited to the type of food the insect feeds on and may or may not have eyes. If the insect has eyes they are either simple or compound.
Activity 4.2: Identifying the features on the head of an insect
What you need
i) Hand lens
ii) Freshly killed adult cockroach, housefly, mosquito, worker bee, butterfly and termite
iii) Notebook

The Thorax of an Insect

The thorax of an insect bears its legs and may or may not have wings.
Activity 4.3: Identifying the features on the thorax of an insect
What you need
i) Hand lens
ii) Freshly killed adult cockroach, housefly, mosquito, worker bee, butterfly and termite
iii) Notebook

What to do
Using a hand lens observe the features of the thorax of the insects provided. Describe the features in the table below.

Chapter summary

• All insects have the same number of legs and body parts.
• The external characteristics of insects can be used to classify them and determine their mode of life.
• Most insects are beneficial and/or harmful to themselves, to other organisms, or to the environment.

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