A little bit of… INSECTS
Raimundo Sepúlveda V.
IPM-Agronomist, U. de Chile.
CHILE (South America)
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.
Figure 1. A “7 pointed-ladybug”, a
good example of insect. Look its
body divided in 3 parts and 6 legs (1).
Entomology is the science that studies Insects and its specialist it is
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.
Figure 2. A “peach (tree) green
aphid”. We see its winged phase
with long antennas and legs (2).
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
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.
Figura 3. A beauty “silvered blue
butterfly” (Heliconius sp.). It is
clasificated into Lepidoptera, due to
its 4 wings with little and coloured
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)
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.