This document provides an introduction to insects. It discusses that insects have colonized Earth for over 400 million years and come in a wide variety of sizes, colors, and designs. The document also summarizes some basic entomology concepts, including that insects generally have 3 body parts (head, thorax, abdomen) and 6 legs. It notes that the science of entomology studies insects and focuses on wing morphology for insect classification. Examples given include the orders Coleoptera and Lepidoptera. The document concludes that there may be more insects than humans on Earth.

1. A little bit of… INSECTS
August, 2013.
(1rst. part)
Raimundo Sepúlveda V.
IPM-Agronomist, U. de Chile.
CHILE (South America)
rsepulvedamipp@gmail.com

2. Introduction…
There are many forms to tackle the great topics of INSECTS.
A classics way is starting with biodiversity of our planet (huge
numbers, different types); another it could be studying the
fossil register with first insects (perhaps with mistakes); or
simply to talk about the successfuly 6 legs-animals
(hexapodes) that live everywhere.
Whatever be the beginning, Insects are special animals that
have known to colonize Earth since aprox. 400 millions years;
even us, the modern man, has not did this. So, we must look
and observe Insects with attention, respect and fascination.

3. Figure 1. A “7 pointed-ladybug”, a
good example of insect. Look its
body divided in 3 parts and 6 legs (1).
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4. General ideas…
Entomology is the science that studies Insects and its specialist it is
called entomologist.
In general, with some exceptions, an Insect has 3 parts: 1) Head, 2)
Thorax y 3) Abdomen. For this reason, some scientists call them
“three segmented animals” (in 3 sections).
The general rule says that they have a external skeleton (exo-
skeleton) of chitin; besides, they have 2 antennas, 6 legs when are
adults and 4 wings, as maximum.
Colours and designs show a great variety and they are related to
their habitats or living places.
Sizes= a very wide range. Insects are 0,25mm up to 360mm long,
aprox. See Figure 2.

5. Figure 2. A “peach (tree) green
aphid”. We see its winged phase
with long antennas and legs (2).
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6. Classification…
All Sciences need Classification (taxonomic or systematics)
because classification put things in order and this make the
study easier. However, there are many kinds of
classifications and the selected-one depends on what we are
looking for.
In Entomology, we usually prefer and remember the design
of insects wings, using the greek word “pteron” (=wing).
Then, with this, entomologists created categories, such as:
Coleoptera (coleos+pteron) and Lepidoptera
(lepidos+pteron), that include (in the same order) “beetles”
and “butterflies”. See Figure 3.

7. Figura 3. A beauty “silvered blue
butterfly” (Heliconius sp.). It is
clasificated into Lepidoptera, due to
its 4 wings with little and coloured
scales (3).
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8. Final comments…
Entomologists have named, at least, a million of Insects.
Others scientists have said “for each person on Earth, there
are millions or billions of insects”. So, we could conclude that
human beings are living on the planet of Insects!.
Have a good day…
(to be continued)

9. Images credits…
1.- 100ceros.blogspot.com
2.- www.ars.usda.gov
3.- logos77.wordpress.com
Recommended links…
1.- http://entomology.ucdavis.edu/
2.- http://www.surmagico.cl/el_color_de_las_mariposas.htm
Recommended books (in Spanish)…
1.- Peña, L. 2007. Introducción al estudio de los Insectos de Chile. Ed.
Universitaria. Santiago, Chile. 264p.
2.- Sepúlveda, R. 2013. Apuntes de la Cátedra “Técnicas de Control de Plagas y
Enfermedades…” UTCh-Inacap. Santiago, Chile. 117p.
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